Category Archives: Cross-listed

Disformal symmetry in the Universe: mimetic gravity and beyond [CL]

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http://arxiv.org/abs/2304.11035


Symmetries play an important role in fundamental physics. In gravity and field theories, particular attention has been paid to Weyl (or conformal) symmetry. However, once the theory contains a scalar field, conformal transformations of the metric can be considered a subclass of a more general type of transformation, so-called disformal transformation. Here, we investigate the implications of pure disformal symmetry in the Universe. We derive the form of general disformal invariant tensors from which we build the most general disformal invariant action. We argue that, in cosmology, disformal symmetry amounts to require that the lapse function is fully replaced by a (time-like) scalar field at the level of the action. We then show that disformal symmetry is in general an exactly equivalent formulation of general mimetic gravity. Lastly, we go beyond mimetic gravity and find that a particular class of invariance leads to seemingly Ostrogradski-like (with higher derivatives) Lagrangians, which are nevertheless absent of Ostrogradski ghosts in a cosmological background, despite having an additional degree of freedom. We also propose an application of our formalism to find new invertible disformal transformations, where the coefficient involves higher derivatives and curvature, further expanding the theory space of scalar-tensor theories.

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G. Domènech and A. Ganz
Mon, 24 Apr 23
33/41

Comments: 21 pages

Slow Contraction and the Weyl Curvature Hypothesis [CL]

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http://arxiv.org/abs/2304.10030


Using the power of numerical relativity, we show that, beginning from generic initial conditions that are far from flat, homogeneous and isotropic and have a large Weyl curvature, a period of slow contraction rapidly drives spacetime towards vanishingly small Weyl curvature as the total energy density grows, thus providing a dynamical mechanism that satisfies the Weyl Curvature Hypothesis. We also demonstrate a tight correlation between the Weyl Curvature Hypothesis and ultralocal behavior for canonical scalar fields with a sufficiently steep negative potential energy density.

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A. Ijjas
Mon, 24 Apr 23
34/41

Comments: 5 pages, 5 figures

Avoiding methane emission rate underestimates when using the divergence method [CL]

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http://arxiv.org/abs/2304.10303


Methane is a powerful greenhouse gas, and a primary target for mitigating climate change in the short-term future due to its relatively short atmospheric lifetime and greater ability to trap heat in Earth’s atmosphere compared to carbon dioxide. Top-down observations of atmospheric methane are possible via drone and aircraft surveys as well as satellites such as the TROPOspheric Monitoring Instrument (TROPOMI). Recent work has begun to apply the divergence method to produce regional methane emission rate estimates. Here we show that spatially incomplete observations of methane can produce negatively biased time-averaged regional emission rate estimates via the divergence method, but that this effect can be counteracted by adopting a procedure in which daily advective fluxes of methane are time-averaged before the divergence method is applied. Using such a procedure with TROPOMI methane observations, we calculate yearly Permian emission rates of 3.1, 2.4 and 2.7 million tonnes per year for the years 2019 through 2021. We also show that highly-resolved plumes of methane can have negatively biased estimated emission rates by the divergence method due to the presence of turbulent diffusion in the plume, but this is unlikely to affect regional methane emission budgets constructed from TROPOMI observations of methane. The results from this work are expected to provide useful guidance for future implementations of the divergence method for emission rate estimation from satellite data – be it for methane or other gaseous species in the atmosphere.

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C. Roberts, R. IJzermans, D. Randell, et. al.
Fri, 21 Apr 23
1/60

Comments: 17 pages, 10 figures, submitted to Environmental Research Letters

GSpyNetTree: A signal-vs-glitch classifier for gravitational-wave event candidates [CL]

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http://arxiv.org/abs/2304.09977


Despite achieving sensitivities capable of detecting the extremely small amplitude of gravitational waves (GWs), LIGO and Virgo detector data contain frequent bursts of non-Gaussian transient noise, commonly known as ‘glitches’. Glitches come in various time-frequency morphologies, and they are particularly challenging when they mimic the form of real GWs. Given the higher expected event rate in the next observing run (O4), LIGO-Virgo GW event candidate validation will require increased levels of automation. Gravity Spy, a machine learning tool that successfully classified common types of LIGO and Virgo glitches in previous observing runs, has the potential to be restructured as a signal-vs-glitch classifier to accurately distinguish between glitches and GW signals. A signal-vs-glitch classifier used for automation must be robust and compatible with a broad array of background noise, new sources of glitches, and the likely occurrence of overlapping glitches and GWs. We present GSpyNetTree, the Gravity Spy Convolutional Neural Network Decision Tree: a multi-CNN classifier using CNNs in a decision tree sorted via total GW candidate mass tested under these realistic O4-era scenarios.

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S. Alvarez-Lopez, A. Liyanage, J. Ding, et. al.
Fri, 21 Apr 23
23/60

Comments: 19 pages, 12 figures, submitted to Classical and Quantum Gravity

Dai-Freed anomaly in the standard model and topological inflation [CL]

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http://arxiv.org/abs/2304.10100


When we impose the discrete symmetry in the standard model we have Dai-Freed global anomalies. However, interestingly if we introduce three right-handed neutrinos we can have an anomaly-free discrete $Z_4$ gauge symmetry. This $Z_4$ symmetry should be spontaneously broken down to the $Z_2$ symmetry to generate the heavy Majorana masses for the right-handed neutrinos. We show that this symmetry breaking naturally generates topological inflation, which is consistent with the CMB observations at present and predicts a significant tensor mode with scalar-tensor ratio $r > 0.03$. The right-handed neutrinos play an important role in reheating processes. The reheating temperature is as high as $\sim 10^8$GeV, and non-thermal leptogenesis successfully takes place.

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M. Kawasaki and T. Yanagida
Fri, 21 Apr 23
32/60

Comments: 9 pages and 2 figures

Black holes in classical general relativity and beyond [CL]

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http://arxiv.org/abs/2304.09984


The Kerr-Newman metric is the unique vacuum solution of the General Relativistic field equations, in which any singularities or spacetime pathologies are hidden behind horizons. They are believed to describe the spacetimes of massive astrophysical objects with no surfaces, which we call black holes. This spacetime, which is defined entirely by the mass, spin, and charge of the black hole, gives rise to a variety of phenomena in the motion of particles and photons outside the horizons that have no Newtonian counterparts. Moreover, the Kerr-Newman spacetime remains remarkably resilient to many attempts in modifying the underlying theory of gravity. The monitoring of stellar orbits around supermassive black holes, the detection of gravitational waves from the coalescence of stellar-mass black holes, and the observation of black-hole shadows in images with horizon-scale resolution, all of which have become possible during the last decade, are offering valuable tools in testing quantitatively the predictions of this remarkable solution to Einstein’s equations.

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D. Psaltis
Fri, 21 Apr 23
35/60

Comments: This chapter is the pre-print of the version currently in production. Please cite this chapter as the following: D. Psaltis. “Black holes in classical general relativity and beyond” in The Encyclopedia of Cosmology (Set 2): Black Holes, edited by Z. Haiman (World Scientific, New Jersey, 2023)

Probing primordial black holes from a first order phase transition through pulsar timing and gravitational wave signals [CL]

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http://arxiv.org/abs/2304.10084


In this work, we assess the sensitivity reach of pulsar timing array (PTA) measurements to probe pointlike primordial black holes (PBHs), with an extended mass distribution, which originate from collapsed Fermi balls that are formed through the aggregation of asymmetric U(1) dark fermions trapped within false vacuum bubbles during a dark first order phase transition (FOPT). The PBH formation scenario is mainly characterized by the dark asymmetry, strength of the FOPT, rate of FOPT, and the percolation temperature. Meanwhile, for PBH masses of interest lying within $10^{-10} M_\odot – 10^{-3}M_\odot$, the relevant signal for PTA measurements is the Doppler phase shift in the timing signal, due to the velocity change induced by transiting PBHs on pulsars. Taking the dark asymmetry parameter to be $10^{-4}$ and $10^{-5}$, we find that percolation temperatures within the 0.1-10 keV range, FOPT rates above $10^3$ times the Hubble parameter at percolation, and FOPT strengths within $10^{-6}-0.1$ can give rise to PBHs that can be probed by an SKA-like PTA observation. On the other hand, the accompanying gravitational wave (GW) signal from the FOPT can be used as a complementary probe, assuming that the peak frequency lies within the $\mathcal{O}(10^{-9})-\mathcal{O}(10^{-6})$ Hz range, and the peak GW abundance is above the peak-integrated sensitivity curves associated with pulsar timing observations that search for stochastic GWs. At the fundamental level, a quartic effective potential for a dark scalar field can trigger the FOPT. By performing a parameter scan, we obtained the class of effective potentials that lead to FOPT scenarios that can be probed by SKA through pulsar timing and GW observations.

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J. Acuña and P. Tseng
Fri, 21 Apr 23
43/60

Comments: 40 pages, 8 figures

Testing the first law of black hole mechanics with gravitational waves [CL]

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http://arxiv.org/abs/2304.10117


GW191219_163120 is a gravitational wave signal that is believed to have originated from a neutron star-black hole (NSBH) coalescence with an extreme mass ratio. In this work, we use data of GW191219_163120 from LIGO and Virgo to test the first law of black hole mechanics by considering the neutron star as a perturbation to the black hole before the merger, and the remnant black hole as a stationary black hole after the merger. Our results demonstrate consistency with the first law of black hole mechanics, with an error level of about 6\% at 68\% credibility and 10\% at 95\% credibility. We also find that the higher the mass ratio of the gravitational wave source, the more consistent our results are with the first law of black hole mechanics. Overall, our study sheds light on the nature of NSBH coalescences and their implications for black hole mechanics.

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C. Wang and F. Shu
Fri, 21 Apr 23
55/60

Comments: 5 pages, 4 figures, 2 tables

Annotated bibliography: Philosophy of Astrophysics [CL]

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http://arxiv.org/abs/2304.10067


The following annotated bibliography contains a reasonably complete survey of contemporary work in the philosophy of astrophysics. Spanning approximately forty years from the early 1980s to the present day, the bibliography should help researchers entering the field to acquaint themselves with its major texts, while providing an opportunity for philosophers already working on astrophysics to expand their knowledge base and engage with unfamiliar material.

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C. Yetman
Fri, 21 Apr 23
59/60

Comments: 28 pages, 79 entries, forthcoming 2023

Universality of Bose-Einstein Condensation and Quenched Formation Dynamics [CL]

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http://arxiv.org/abs/2304.09541


The emergence of macroscopic coherence in a many-body quantum system is a ubiquitous phenomenon across different physical systems and scales. This Chapter reviews key concepts characterizing such systems (correlation functions, condensation, quasi-condensation) and applies them to the study of emerging non-equilibrium features in the dynamical path towards such a highly-coherent state: particular emphasis is placed on emerging universal features in the dynamics of conservative and open quantum systems, their equilibrium or non-equilibrium nature, and the extent that these can be observed in current experiments with quantum gases. Characteristic examples include symmetry-breaking in the Kibble-Zurek mechanism, coarsening and phase-ordering kinetics, and universal spatiotemporal scalings around non-thermal fixed points and in the context of the Kardar- Parisi-Zhang equation; the Chapter concludes with a brief review of the potential relevance of some of these concepts in modelling the large-scale distribution of dark matter in the universe.

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N. Proukakis
Thu, 20 Apr 23
11/57

Comments: Invited contribution to the Encyclopedia of Condensed Matter Physics (Elsevier, 2nd Edition)

Comment on "Observational Evidence for Cosmological Coupling of Black Holes and its Implications for an Astrophysical Source of Dark Energy" [CL]

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http://arxiv.org/abs/2304.09817


It was recently claimed that black holes can explain the accelerated expansion of the universe. Here we point out that this claim is based on a confusion about the principle of least action, undermining the link between black holes and dark energy.

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T. Mistele
Thu, 20 Apr 23
12/57

Comments: 5 pages

Neutron Stars on Modified Teleparallel Gravity [CL]

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http://arxiv.org/abs/2301.06432


We investigate compact objects in modified teleparallel gravity with realistic equations of state. We propose a modification on Teleparallel Equivalent of General Relativity, then an appropriate tetrad is applied on the field equations. A specific set of relations showing a equivalency between our gravitational model and the New General Relativity is found. The conservation equation implies that our Tolman-Oppenheimer-Volkoff equations are presented with an effective pressure and energy density, where a free parameter \b{eta}3 is used to construct them. Numerical analysis using realistic equations of state is made, the behavior of mass, radius and the relation mass-radius as functions of \b{eta}3 is also investigated.

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S. Vilhena, S. Duarte, M. Dutra, et. al.
Thu, 20 Apr 23
17/57

Comments: 8 pages, 5 figures

The Primordial Black Holes that Disappeared: Connections to Dark Matter and MHz-GHz Gravitational Waves [CL]

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http://arxiv.org/abs/2304.09194


In the post-LIGO era, there has been a lot of focus on primordial black holes (PBHs) heavier than $\sim 10^{15}$g as potential dark matter (DM) candidates. We point out that the branch of the PBH family that disappeared – PBHs lighter than $\sim 10^9$g that ostensibly Hawking evaporated away in the early Universe – also constitute an interesting frontier for DM physics. Hawking evaporation itself serves as a portal through which such PBHs can illuminate new physics, for example by emitting dark sector particles. Taking a simple DM scalar singlet model as a template, we compute the abundance and mass of PBHs that could have provided, by Hawking evaporation, the correct DM relic density. We consider two classes of such PBHs: those originating from curvature perturbations generated by inflation, and those originating from false vacuum collapse during a first-order phase transition. For PBHs of both origins we compute the gravitational wave (GW) signals emanating from their formation stage: from second-order effects in the case of curvature perturbations, and from sound waves in the case of phase transitions. The GW signals have peak frequencies in the MHz-GHz range typical of such light PBHs. We compute the strength of such GWs compatible with the observed DM relic density, and find that the GW signal morphology can in principle allow one to distinguish between the two PBH formation histories.

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T. Gehrman, B. Haghi, K. Sinha, et. al.
Thu, 20 Apr 23
19/57

Comments: 23 pages + references, 8 figures

Clockwork Cosmology [CL]

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http://arxiv.org/abs/2304.09205


The higher order generalisation of the clockwork mechanism to gravitational interactions provides a means to generate an exponentially suppressed coupling to matter from a fundamental theory of multiple interacting gravitons, without introducing large hierarchies in the underlying potential and without the need for a dilaton, suggesting a possible application to the hierarchy problem. We work in the framework of ghost free multi-gravity with “nearest-neighbour” interactions, and present a formalism by which one is able to construct potentials such that the theory will always exhibit this clockwork effect. We also consider cosmological solutions to the general theory, where all metrics are of FRW form, with site-dependent scale factors/lapses. We demonstrate the existence of multiple deSitter vacua where all metrics share the same Hubble parameter, and we solve the modified Einstein equations numerically for an example clockwork model constructed using our formalism, finding that the evolution of the metric that matter couples to is essentially equivalent to that of general relativity at the modified Planck scale. It is important to stress that while we focus on the application to clockwork theories, our work is entirely general and facilitates finding cosmological solutions to any ghost free multi-gravity theory with “nearest-neighbour” interactions. Moreover, we clarify previous work on the continuum limit of the theory, which is generically a scalar-tensor braneworld, using the Randall-Sundrum model as a special case and showing how the discrete-clockwork cosmological results map to the continuum results in the appropriate limit.

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K. Wood, P. Saffin and A. Avgoustidis
Thu, 20 Apr 23
27/57

Comments: 48 pages, 4 figures

Dark matter effects in modified teleparallel gravity [CL]

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http://arxiv.org/abs/2304.07364


This work investigates dark matter (DM) effects in compact objects in modified teleparallel gravity (MTG) in which a modification of Teleparallel Equivalent to General Relativity is used. We applied a tetrad to the modified field equations where a set of relations is found. The conservation equation allows us to rewrite our Tolman-Oppenheimer-Volkoff equations with an effective gravitational coupling constant. As input to these new equations, we use a relativistic mean-field (RMF) model with dark matter content included, obtained from a Lagrangian density with both, hadronic and dark particle degrees of freedom, as well as the Higgs boson, used as a mediator in both sectors of the theory. Through numerical calculations, we analyze the mass-radius diagrams obtained from different parametrizations of the RMF-DM model, generated by assuming different values of the dark particle Fermi momentum and running the free parameter coming from the MTG. Our results show that it is possible for the system simultaneously support more DM content, and be compatible with recent astrophysical data provided by LIGO and Virgo Collaboration, as well as by NASA’s Neutron star Interior Composition Explorer (NICER).

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S. Vilhena, M. Dutra, O. Lourenço, et. al.
Thu, 20 Apr 23
44/57

Comments: 8 pages, 2 figures

BCS in the Sky: Signatures of Inflationary Fermion Condensation [CL]

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http://arxiv.org/abs/2304.09428


We consider a Bardeen-Cooper-Schrieffer (BCS)-like model in the inflationary background. We show that with an axial chemical potential, the attractive quartic fermion self-interaction can lead to a BCS-like condensation. In the de Sitter (dS) limit of inflation, we perform the first computation of the non-perturbative effective potential that includes the full spacetime curvature effects in the presence of the chemical potential. The corresponding BCS phase transition is always first-order, when the varying Hubble is interpreted as an effective Gibbons-Hawking temperature of dS spacetime. In the condensate phase, the theory can be understood from UV and IR sides as fermionic and bosonic, respectively. This leads to distinctive signatures in the primordial non-Gaussianity of curvature perturbations. Namely, the oscillatory cosmological collider signal is smoothly turned off at a finite momentum ratio, since different momentum ratios effectively probe different energy scales. In addition, such BCS phase transitions can also source stochastic gravitational waves, feasible for future experiments.

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X. Tong, Y. Wang, C. Zhang, et. al.
Thu, 20 Apr 23
48/57

Comments: 30 pages, 8 figures

Gauge/frame invariant variables for the numerical relativity study of cosmological spacetimes [CL]

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http://arxiv.org/abs/2304.07616


To numerically evolve the full Einstein equations (or modifications thereof), simulations of cosmological spacetimes must rely on a particular formulation of the field equations combined with a specific gauge/frame choice. Yet truly physical results cannot depend on the given formulation or gauge/frame choice. In this paper, we present a resolution of the gauge problem and, as an example, numerically implement it to evaluate our previous work on contracting spacetimes.

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A. Ijjas
Wed, 19 Apr 23
14/58

Comments: 22 pages, 8 figures

Exorcising the Ghost Condensate Dark Energy with a Sextic Dispersion Relation [CL]

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http://arxiv.org/abs/2304.07344


The universe’s current acceleration is a pretty recent phenomenon in cosmological time scales. This means that the modes that have left our horizon since the beginning of the contemporary acceleration phase, have not really reached the exact IR limit. Noting this observation, we reconsider the possibility of having a ghost condensate as dark energy with a sixth-order dispersion relation. Looking at the three-point function of such a theory, we obtain the constraints on the coefficient of the sixth-order dispersion relation to avoid strong coupling. Such a ghost condensate if coupled to the standard model fields, induces a constant Lorentz-violating spin-dependent force, which can gravitate or anti-gravitate.

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A. Ashoorioon and A. Yousefi-Sostani
Wed, 19 Apr 23
25/58

Comments: 15+1 pages

Effective description of generalized disformal theories [CL]

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http://arxiv.org/abs/2304.08624


Generalized disformal transformations enable us to construct the generalized disformal Horndeski theories, which form the most general class of ghost-free scalar-tensor theories to this date. We extend the effective field theory (EFT) of cosmological perturbations to incorporate these generalized disformal Horndeski theories. The main difference from the conventional EFT is that our extended EFT involves operators with higher spatial derivatives of the lapse function. Our EFT also accommodates the generalized disformal transformation of U-DHOST theories.

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K. Takahashi, M. Minamitsuji and H. Motohashi
Wed, 19 Apr 23
26/58

Comments: 14 pages

Bayesian averaging for ground state masses of atomic nuclei in a Machine Learning approach [CL]

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http://arxiv.org/abs/2304.08546


We present global predictions of the ground state mass of atomic nuclei based on a novel Machine Learning (ML) algorithm. We combine precision nuclear experimental measurements together with theoretical predictions of unmeasured nuclei. This hybrid data set is used to train a probabilistic neural network. In addition to training on this data, a physics-based loss function is employed to help refine the solutions. The resultant Bayesian averaged predictions have excellent performance compared to the testing set and come with well-quantified uncertainties which are critical for contemporary scientific applications. We assess extrapolations of the model’s predictions and estimate the growth of uncertainties in the region far from measurements.

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M. Mumpower, M. Li, T. Sprouse, et. al.
Wed, 19 Apr 23
28/58

Comments: 15 pages, 10 figures, comments welcome

Tests of modified gravitational wave propagations with gravitational waves [CL]

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http://arxiv.org/abs/2304.09025


Any violation of the fundamental principles of general relativity (GR), including the violations of the equivalence principle and parity/Lorentz symmetries, could induce possible derivations in the gravitational wave (GW) propagations so they can be tested/constrained directly by the GW data. In this letter, we present a universal parametrization for characterizing possible derivations from GW propagations in GR. This parametrization provides a general framework for exploring possible modified GW propagations arising from a large number of modified theories of gravity. With this parameterization, we construct the modified GW waveforms generated by the coalescence of compact binaries with the effects of the gravitational parity/Lorentz violations, then analyze the open data of compact binary merging events detected by LIGO/Virgo/KAGRA collaboration. We do not find any signatures of gravitational parity/Lorentz violations, thereby allowing us to place several of the most stringent constraints on parity/Lorentz violations in gravity and a first constraint on the Lorentz-violating damping effect in GW. This also represents the most comprehensive tests on the modified GW propagations.

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T. Zhu, W. Zhao, J. Yan, et. al.
Wed, 19 Apr 23
36/58

Comments: 6 pages, 3 tables, and 1 figure

Astrophysical neutrino point sources as a probe of new physics [CL]

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http://arxiv.org/abs/2304.08533


Recently, the IceCube collaboration observed a neutrino excess in the direction of NGC 1068 with high statistical significance. This constitutes the second detection of an astrophysical neutrino point source after the discovery of a variable emission originating from the blazar TXS~0506+056. Neutrinos emitted by these sources traverse huge, well-determined distances on their way to Earth. This makes them a promising tool to test new physics in the neutrino sector. We consider secret interactions with the cosmic neutrino background and discuss their impact on the flux of neutrino point sources. The observation of emission from NGC 1068 and TXS 0506+056 can then be used to put limits on the strength of the interaction. We find that our ignorance of the absolute neutrino masses has a strong impact and, therefore, we present limits in two benchmark scenarios with the sum of the neutrino masses around their lower and upper limits.

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C. Döring and S. Vogl
Wed, 19 Apr 23
40/58

Comments: 7 pages + appendix, 5 figures

LIGO-VIRGO constraints on dark matter and leptogenesis triggered by a first order phase transition at high scale [CL]

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http://arxiv.org/abs/2304.08888


We study the possibility of constraining a scenario with high scale first order phase transition (FOPT) responsible for the cogenesis of baryon and dark matter using gravitational wave (GW) (non)-observations. While the FOPT at high scale is responsible for generating baryon asymmetry through leptogenesis and dark matter via the \textit{mass-gain} mechanism, the resulting GW spectrum falls within the ongoing LIGO-VIRGO experimental sensitivity. The dark matter is preferred to be in the non-thermal ballpark with sub-GeV masses and the criteria of successful dark matter relic rules out a large portion of the parameter space consistent with high scale FOPT and successful leptogenesis. Some part of the parameter space allowed from dark matter and leptogenesis criteria also gives rise to a large signal-to-noise ratio at ongoing experiments and hence can be disfavoured in a conservative way from the non-observation of such stochastic GW background. Future data from ongoing and planned experiments will offer a complementary and indirect probe of the remaining parameter space which is typically outside the reach of any direct experimental probe.

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D. Borah, A. Dasgupta and I. Saha
Wed, 19 Apr 23
42/58

Comments: 15 pages, 5 captioned figures

Anisotropic power-law inflation for a generalized model of two scalar and two vector fields [CL]

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http://arxiv.org/abs/2304.08874


Cosmological implication of a generalized model of two scalar and two vector fields, in which both scalar fields are non-minimally coupled to each vector field, is studied in this paper. In particular, we will seek an anisotropic power-law inflationary solution to this model. Furthermore, the stability of the obtained solution will be examined by using the dynamical system approach. As a result, we will show that this solution turns out to be stable and attractive during the inflationary phase as expected due to the existence of the unusual couplings between two scalar and two vector fields. Remarkably, we will point out that the existence of phantom field will lead to an instability of the corresponding anisotropic power-law inflation.

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T. Do and W. Kao
Wed, 19 Apr 23
51/58

Comments: 20 pages, 6 figures. Comments are welcome. arXiv admin note: text overlap with arXiv:2110.13516

On the seed population of solar energetic particles in the inner heliosphere [CL]

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http://arxiv.org/abs/2304.09098


Particles measured in large gradual solar energetic particle (SEP) events are believed to be predominantly accelerated at shocks driven by coronal mass ejections (CMEs). Ion charge state and composition analyses suggest that the origin of the seed particle population for the mechanisms of particle acceleration at CME-driven shocks is not the bulk solar wind thermal material, but rather a suprathermal population present in the solar wind. This suprathermal population could result from remnant material accelerated in prior solar flares and/or preceding CME-driven shocks. In this work, we examine the distribution of this suprathermal particle population in the inner heliosphere by combining a magnetohydrodynamic (MHD) simulation of the solar wind and a Monte-Carlo simulation of particle acceleration and transport. Assuming that the seed particles are uniformly distributed near the Sun by solar flares of various magnitudes, we study the longitudinal distribution of the seed population at multiple heliocentric distances. We consider a non-uniform background solar wind, consisting of fast and slow streams that lead to compression and rarefaction regions within the solar wind. Our simulations show that the seed population at a particular location (e.g., 1 au) is strongly modulated by the underlying solar wind configuration. Corotating interaction regions (CIRs) and merged interactions regions (MIRs) can strongly alter the energy spectra of the seed particle populations. In addition, cross-field diffusion plays an important role in mitigating strong variations of the seed population in both space and energy.

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N. Wijsen, G. Li, Z. Ding, et. al.
Wed, 19 Apr 23
52/58

Comments: 20 pages, 7 figures

Trajectories of astroparticles in pseudo-Finsler spacetime with the most general modified dispersion [CL]

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http://arxiv.org/abs/2304.08676


Finsler geometry is a natural and fundamental generalization of Riemann geometry, and is a tool to research Lorentz invariance violation. We find the connection between the most general modified dispersion relation and a pseudo-Finsler structure, and then we calculate the arrival time delay of astroparticles with different modified dispersion relations in the framework of Finsler geometry. The result suggests that the time delay is irrelevant with the exact form of the modified dispersion relation. If the modified term becomes 0 when $E=p$, there is no arrival time difference, otherwise the time delays only depend on the Lorentz violation scale and the order at which the Lorentz invariance breaks.

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J. Zhu and B. Ma
Wed, 19 Apr 23
53/58

Comments: 9 pages, no figure, version for journal publication

Hot and highly magnetized neutron star matter properties with Skyrme interactions [CL]

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http://arxiv.org/abs/2304.08776


We study the properties of hot and dense neutron star matter under the presence of strong magnetic fields using two Skyrme interactions, namely the LNS and the BSk21 ones. Asking for $\beta$–stability and charge neutrality, we construct the equation of state of the system and analyze its composition for a range of densities, temperatures and magnetic field intensities of interest for the study of supernova and proto-neutron star matter, with a particular interest on the degree of spin-polarization of the different components. The results show that system configurations with larger fractions of spin up protons and spin down neutrons and electrons are energetically favored over those with larger fractions of spin down protons and spin up neutrons and electrons. The effective mass of neutrons and protons is found to be in general larger for the more abundant of their spin projection component, respectively, spin down neutrons and spin up protons. The effect of the magnetic field on the Helmhotz total free energy density, pressure and isothermal compressibility of the system is almost negligible for all the values of the magnetic field considered.

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O. Benvenuto, E. Bauer and I. Vidaña
Wed, 19 Apr 23
55/58

Comments: 10 pages, 8 figures, 2 tables

Geoeffectiveness of Interplanetary Shocks Controlled by Impact Angles: Past Research, Recent Advancements, and Future Work [CL]

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http://arxiv.org/abs/2304.08254


Interplanetary (IP) shocks are disturbances commonly observed in the solar wind. IP shock impacts can cause a myriad of space weather effects in the Earth’s magnetopause, inner magnetosphere, ionosphere, thermosphere, and ground magnetic field. The shock impact angle, measured as the angle the shock normal vector performs with the Sun-Earth line, has been shown to be a very important parameter that controls shock geoeffectivess. An extensive review provided by Oliveira and Samsonov (2018) summarized all the work known at the time with respect to shock impact angles and geomagnetic activity; however, this topic has had some progress since Oliveira and Samsonov (2018) and the main goal of this mini review is to summarize all achievements to date in the topic to the knowledge of the author. Finally, this mini review also brings a few suggestions and ideas for future research in the area of IP shock impact angle geoeffectiveness.

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D. Oliveira
Tue, 18 Apr 23
2/80

Comments: 13 pages, 1 figuew

Freeze-in baryogenesis and early matter domination [CL]

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http://arxiv.org/abs/2304.07345


The freeze-in mechanism has been shown to allow the simultaneous generation of cosmic dark matter and a viable matter-antimatter asymmetry in the universe. When the underlying interactions are described by higher-dimensional, non-renormalizable operators, the relevant freeze-in processes take place close to the highest considered cosmic temperatures. In this paper we study how the presence of a fluid that temporarily dominates the energy content of the early universe affects the predictions of this “Ultraviolet Freeze-In Baryogenesis” scenario. We find that this additional cosmic component has a significant impact on the predictions of concrete microscopic models, allowing for reheating temperatures which are much lower than those required in the simplest cosmological scenario. Moreover, we show that inflationary observables can constrain the parameter space of such models, once the latter are examined in conjunction with concrete models of inflation.

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I. Dalianis, A. Goudelis, D. Karamitros, et. al.
Tue, 18 Apr 23
25/80

Comments: 25 pages, 6 figures

Quarkyonic Model for Neutron Star Matter: A Relativistic Mean-Field Approach [CL]

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http://arxiv.org/abs/2304.08223


The concept of quarkyonic matter presents a promising alternative to the conventional models used to describe high-density matter and provides a more nuanced and detailed understanding of the properties of matter under extreme conditions that exist in astrophysical bodies. The aim of this study is to showcase the effectiveness of utilizing the quarkyonic model, in combination with the relativistic mean-field formalism, to parameterize the equation of state at high densities. Through this approach, we intend to investigate and gain insights into various fundamental properties of a static neutron star, such as its compositional ingredients, speed of sound, mass-radius profile, and tidal deformability. The obtained results revealed that the quarkyonic matter equation of state (EOS) is capable of producing a heavy neutron star with the mass range of $\sim$ $2.8 M_\odot$. The results of our inquiry have demonstrated that the EOS for quarkyonic matter not only yields a neutron star with a significantly high mass but also showcases a remarkable degree of coherence with the conformal limit of the speed of sound originating from deconfined QCD matter. Furthermore, we have observed that the tidal deformability of the neutron star, corresponding to the EOSs of quarkyonic matter, is in excellent agreement with the observational constraints derived from the GW170817 and GW190425 events. This finding implies that the quarkyonic model is capable of forecasting the behavior of neutron stars associated with binary merger systems. This aspect has been meticulously scrutinized in terms of merger time, gravitational wave signatures, and collapse times using numerical relativity simulations.

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A. Kumar, D. Dey, S. Haque, et. al.
Tue, 18 Apr 23
29/80

Comments: N/A

Exploring the multi-band gravitational wave background with a semi-analytic galaxy formation model [CL]

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http://arxiv.org/abs/2304.08333


The compact binary systems, spanning from the stellar to supermassive black hole, encode a wealth of information concerning stellar evolution, galaxy formation and evolution, and cosmology. An enormous number of these systems, both resolved and unresolved, emit substantial gravitational waves during their final evolutionary stages, thereby creating a stochastic gravitational wave background (SGWB). We calculate the merger rates of stellar compact binaries and massive black hole binaries using a semi-analytic galaxy formation model — Galaxy Assembly with Binary Evolution (GABE) in a unified and self-consistent approach, followed by an estimation of the multi-band SGWB contributed by the binary systems. We find that the amplitudes of the principal peaks of the SGWB energy density are within one order of magnitude $\Omega_{GW} \sim 10^{-9}- 10^{-8}$. This SGWB can be easily detected by the Square Kilometre Array (SKA), as well as planned interferometric detectors, such as the Einstein Telescope (ET) and the Laser Interferometer Space Antenna (LISA). The energy density of this background varies as $\Omega_{GW} \propto f^{2/3}$ in the SKA band. The shape of the SGWB spectrum in the frequency range $\sim[10^{-4}$,$1]$Hz could allow the space-based detector LISA to distinguish the black hole seed models. The amplitude of the SGWB from merging stellar binary black holes (BBHs) at $\sim 100$ Hz is approximately 10 and 100 times greater than those from merging binary neutron stars (BNSs) and neutron-star-black-hole (NSBH) mergers, respectively.

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Z. Li, Z. Jiang, X. Fan, et. al.
Tue, 18 Apr 23
36/80

Comments: 9 pages, 4 figures

Revisiting the Lithium abundance problem in Big-Bang nucleosynthesis [CL]

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http://arxiv.org/abs/2304.08032


One of the three testaments in favor of the big bang theory is the prediction of the primordial elemental abundances in the big-bang nucleosynthesis (BBN). The Standard BBN is a parameter-free theory due to the precise knowledge of the baryon-to-photon ratio of the Universe obtained from studies of the anisotropies of cosmic microwave background radiation. Although the computed abundances of light elements during primordial nucleosynthesis and those determined from observations are in good agreement throughout a range of nine orders of magnitude, there is still a disparity of $^7$Li abundance overestimated by a factor of $\sim 2.5$ when calculated theoretically. The number of light neutrino flavors, the neutron lifetime and the baryon-to-photon ratio in addition to the astrophysical nuclear reaction rates determine the primordial abundances. We previously looked into the impact of updating baryon-to-photon ratio and neutron lifetime and changing quite a few reaction rates on the yields of light element abundances in BBN. In this work, calculations are performed using new reaction rates for $^3$H(p,$\gamma$)$^4$He, $^6$Li(p,$\gamma$)$^7$Be, $^7$Be(p,$\gamma$)$^8$B, $^{13}$N(p,$\gamma$)$^{14}$O, $^7$Li(n,$\gamma$)$^8$Li and $^{11}$B(n,$\gamma$)$^{12}$B along with the latest measured value of neutron lifetime. We observe from theoretical calculations that these changes result in marginal improvement over a sizable twelve percent reduction in the abundance of $^7$Li achieved earlier.

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V. Singh, D. Bhowmick and D. Basu
Tue, 18 Apr 23
40/80

Comments: 6 pages including 1 table. arXiv admin note: text overlap with arXiv:1708.05567

Effective field theories for dark matter pairs in the early universe: cross sections and widths [CL]

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http://arxiv.org/abs/2304.00113


In order to predict the cosmological abundance of dark matter, an estimation of particle rates in an expanding thermal environment is needed. For thermal dark matter, the non-relativistic regime sets the stage for the freeze-out of the dark matter energy density. We compute transition widths and annihilation, bound-state formation, and dissociation cross sections of dark matter fermion pairs in the unifying framework of non-relativistic effective field theories at finite temperature, with the thermal bath modeling the thermodynamical behaviour of the early universe. We reproduce and extend some known results for the paradigmatic case of a dark fermion species coupled to dark gauge bosons. The effective field theory framework allows to highlight their range of validity and consistency, and to identify some possible improvements.

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S. Biondini, N. Brambilla, G. Qerimi, et. al.
Tue, 18 Apr 23
44/80

Comments: 62 pages, 20 figures

LISAmax: Improving the Gravitational-Wave Sensitivity by Two Orders of Magnitude [CL]

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http://arxiv.org/abs/2304.08287


Within its Voyage 2050 planning cycle, the European Space Agency (ESA) is considering long-term large class science mission themes. Gravitational-wave astronomy is among the topics under study. This paper presents “LISAmax”, a gravitational-wave interferometer concept consisting of three spacecraft located close to the Sun-Earth libration points L3, L4 and L5, forming a triangular constellation with an arm length of 259 million kilometers (to be compared to LISA’s 2.5 million kilometer arms). This is the largest triangular formation that can be reached from Earth without a major leap in mission complexity and cost. The sensitivity curve of such a detector is at least two orders of magnitude lower in amplitude than that of LISA. Depending on the choice of other instrument parameters, this makes the detector sensitive to gravitational waves in the micro-Hertz range and opens a new window for gravitational-wave astronomy, not covered by any other planned detector concept. We analyze in detail the constellation stability for a 10-year mission in the full numerical model and compute the orbit transfers using a European launcher and chemical propulsion. The payload design parameters are assessed, and the expected sensitivity curve is compared with a number of potential gravitational-wave sources. No show stoppers are identified at this point of the analysis.

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W. Martens, M. Khan and J. Bayle
Tue, 18 Apr 23
45/80

Comments: 18 pages, 11 figures

Tabulated Equations of State From Models Informed by Chiral Effective Field Theory [CL]

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http://arxiv.org/abs/2304.07836


We construct four equation of state (EoS) tables, tabulated over a range of temperatures, densities, and charge fractions, relevant for neutron star applications such as simulations of neutron star mergers. The EoS are computed from a relativistic mean-field theory constrained by the pure neutron matter EoS from chiral effective field theory, inferred properties of isospin-symmetric nuclear matter, and astrophysical observations of neutron star structure. To model nuclear matter at low densities, we attach an EoS that models inhomogeneous nuclear matter at arbitrary temperatures and charge fractions. The four EoS tables we develop are available from the CompOSE EoS repository https://compose.obspm.fr/eos/297 and https://gitlab.com/ahaber/qmc-rmf-tables.

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M. Alford, L. Brodie, A. Haber, et. al.
Tue, 18 Apr 23
47/80

Comments: 8 pages, 2 figures

Measurement of the Cross-Correlation Angular Power Spectrum Between the Stochastic Gravitational Wave Background and Galaxy Over-Density [CL]

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http://arxiv.org/abs/2304.07621


We study the cross-correlation between the stochastic gravitational-wave background (SGWB) generated by binary black hole (BBH) mergers across the universe and the distribution of galaxies across the sky. We use the anisotropic SGWB measurement obtained using data from the third observing run (O3) of Advanced LIGO detectors and galaxy over-density obtained from the Sloan Digital Sky Survey (SDSS) spectroscopic catalog. We compute, for the first time, the angular power spectrum of their cross-correlation. Instead of integrating the SGWB across frequencies, we analyze the cross-correlation in 10 Hz wide SGWB frequency bands to study the frequency dependence of the cross-correlation angular power spectrum. Finally, we compare the observed cross-correlation to the spectra predicted by astrophysical models. We apply a Bayesian formalism to explore the parameter space of the theoretical models, and we set constraints on a set of (effective) astrophysical parameters describing the galactic process of gravitational wave (GW) emission. Parameterizing with a Gaussian function the astrophysical kernel describing the local process of GW emission at galactic scales, we find the 95\% upper limit on kernel amplitude to be $2.7 \times 10^{-32}$ erg cm$^{-3}$s$^{-1/3}$ when ignoring the shot noise in the GW emission process, and $2.16 \times 10^{-32}$ erg cm$^{-3}$s$^{-1/3}$ when the shot noise is included in the analysis. As the sensitivity of the LIGO-Virgo-KAGRA network improves, we expect to be able to set more stringent bounds on this kernel function and constrain its parameters.

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K. Z.Yang, J. Suresh, G. Cusin, et. al.
Tue, 18 Apr 23
49/80

Comments: 19 pages, 12 figures

Big Bang initial conditions and self-interacting hidden dark matter [CL]

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http://arxiv.org/abs/2304.08454


A variety of supergravity and string models involve hidden sectors where the hidden sectors may couple feebly with the visible sectors via a variety of portals. While the coupling of the hidden sector to the visible sector is feeble its coupling to the inflaton is largely unknown. It could couple feebly or with the same strength as the visible sector which would result in either a cold or a hot hidden sector at the end of reheating. These two possibilities could lead to significantly different outcomes for observables. We investigate the thermal evolution of the two sectors in a cosmologically consistent hidden sector dark matter model where the hidden sector and the visible sector are thermally coupled and their thermal evolution occurs without the assumption of separate entropy conservation for each sector. Within this framework we analyze several phenomena to illustrate their dependence on the initial conditions. These include the allowed parameter space of models, dark matter relic density, proton-dark matter cross section, effective massless neutrino species at BBN time, self-interacting dark matter cross-section, where self-interaction occurs via exchange of dark photon, and Sommerfeld enhancement. Finally fits to the velocity dependence of dark matter cross sections from galaxy scales to the scale of galaxy clusters is given. The analysis indicates significant effects of the initial conditions on the observables listed above. The analysis is carried out within the framework where dark matter is constituted of dark fermions and the mediation between the visible and the hidden sector occurs via the exchange of dark photons. The techniques discussed here may have applications for a wider class of hidden sector models using different mediations between the visible and the hidden sectors to explore the impact of Big Bang initial conditions on observable physics.

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J. Li and P. Nath
Tue, 18 Apr 23
52/80

Comments: 29 pages,10 figures

Search for gravitational-lensing signatures in the full third observing run of the LIGO-Virgo network [CL]

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http://arxiv.org/abs/2304.08393


Gravitational lensing by massive objects along the line of sight to the source causes distortions of gravitational wave-signals; such distortions may reveal information about fundamental physics, cosmology and astrophysics. In this work, we have extended the search for lensing signatures to all binary black hole events from the third observing run of the LIGO–Virgo network. We search for repeated signals from strong lensing by 1) performing targeted searches for subthreshold signals, 2) calculating the degree of overlap amongst the intrinsic parameters and sky location of pairs of signals, 3) comparing the similarities of the spectrograms amongst pairs of signals, and 4) performing dual-signal Bayesian analysis that takes into account selection effects and astrophysical knowledge. We also search for distortions to the gravitational waveform caused by 1) frequency-independent phase shifts in strongly lensed images, and 2) frequency-dependent modulation of the amplitude and phase due to point masses. None of these searches yields significant evidence for lensing. Finally, we use the non-detection of gravitational-wave lensing to constrain the lensing rate based on the latest merger-rate estimates and the fraction of dark matter composed of compact objects.

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L. Collaboration, V. Collaboration, K. Collaboration, et. al.
Tue, 18 Apr 23
54/80

Comments: 28 pages, 11 figures

Accurate Inverse-Compton Models Strongly Enhance Leptophilic Dark Matter Signals [CL]

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http://arxiv.org/abs/2304.07317


The annihilation of TeV-scale leptophilic dark matter into electron-positron pairs (hereafter $e^+e^-$) will produce a sharp cutoff in the local cosmic-ray $e^+e^-$ spectrum at an energy matching the dark matter mass. At these high energies, $e^+e^-$ cool quickly due to synchrotron interactions with magnetic fields and inverse-Compton scattering with the interstellar radiation field. These energy losses are typically modelled as a continuous process. However, inverse-Compton scattering is a stochastic energy-loss process where interactions are rare but catastrophic. We show that when inverse-Compton scattering is modelled as a stochastic process, the expected $e^+e^-$ flux from dark matter annihilation is about a factor of $\sim$2 larger near the dark matter mass than in the continuous model. This greatly enhances the detectability of heavy dark matter.

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I. John and T. Linden
Tue, 18 Apr 23
61/80

Comments: 7 pages, 9 figures. Appendix adds 4 pages, 3 figures. To be submitted

Light cold dark matter from non-thermal decay [CL]

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http://arxiv.org/abs/2304.07462


We investigate the mass range and the corresponding free-streaming length scale of dark matter produced non-thermally from decay of heavy objects which can be either dominant or sub-dominant at the moment of decay. We show that the resulting dark matter could be very light well below keV scale with a free-streaming length satisfying the Lyman-{\alpha} constraints. We demonstrate two explicit examples for such light cold dark matter.

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K. Choi, J. Gong, J. Joh, et. al.
Tue, 18 Apr 23
68/80

Comments: 8 pages, 4 figures

Climatologies of Various OH Lines From About 90,000 X-shooter Spectra [CL]

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http://arxiv.org/abs/2304.08206


The nocturnal mesopause region of the Earth’s atmosphere radiates chemiluminescent emission from various roto-vibrational bands of hydroxyl (OH), which is therefore a good tracer of the chemistry and dynamics at the emission altitudes. Intensity variations can, e.g., be caused by the general circulation, gravity waves, tides, planetary waves, and the solar activity. While the basic OH response to the different dynamical influences has been studied quite frequently, detailed comparisons of the various individual lines are still rare. Such studies can improve our understanding of the OH-related variations as each line shows a different emission profile. We have therefore used about 90,000 spectra of the X-shooter spectrograph of the Very Large Telescope at Cerro Paranal in Chile in order to study 10 years of variations of 298 OH lines. The analysis focuses on climatologies of intensity, solar cycle effect, and residual variability (especially with respect to time scales of hours and about 2 days) for day of year and local time. For a better understanding of the resulting variability patterns and the line-specific differences, we applied decomposition techniques, studied the variability depending on time scale, and calculated correlations. As a result, the mixing of thermalized and nonthermalized OH level populations clearly influences the amplitude of the variations. Moreover, the local times of the variability features shift depending on the effective line emission height, which can mainly be explained by the propagation of the migrating diurnal tide. This behavior also contributes to remarkable differences in the effective solar cycle effect.

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S. Noll, C. Schmidt, W. Kausch, et. al.
Tue, 18 Apr 23
70/80

Comments: 35 single-column pages and 12 figures; accepted for publication in J. Geophys. Res. Atmos

Properties of First-Order Hadron-Quark Phase Transition from Directly Inverting Neutron Star Observables [CL]

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http://arxiv.org/abs/2304.07381


By directly inverting the observational data of several neutron star observables in the three dimensional parameter space of the constant speed of sound (CSS) model while fixing all hadronic Equation of State parameters at their currently known most probable values, we constrain the three parameters of the CSS model and their correlations. Using two lower radius limits of $R_{2.01}=11.41$ km and $R_{2.01}=12.2$ km for PSR J0740+6620 obtained from two independent analyses using different approaches by the Neutron Star Interior Composition Explorer (NICER) Collaboration, the speed of sound squared $c_{\rm QM}^2$ in quark matter is found to have a lower limit of $0.35$ and $0.43$ in unit of $c^2$, respectively, above its conformal limit of $c_{\rm QM}^2<1/3$. Moreover, an approximately linear correlation between the first-order hadron-quark transition density $\rho_t$ and its strength $\Delta\varepsilon$ is found.

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N. Zhang and B. Li
Tue, 18 Apr 23
75/80

Comments: 7 pages with 4 figures

How the Moon Impacts Subsea Communication Cables [CL]

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http://arxiv.org/abs/2304.06905


We report tidal-induced latency variations on a transpacific subsea cable. Week-long recordings with a precision phase meter suggest length changes in the sub-meter range caused by the Poisson effect. The described method adds to the toolbox for the new field >>optical oceanic seismology<<.

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L. Moeller
Mon, 17 Apr 23
2/51

Comments: N/A

Hunting the stochastic gravitational wave background in pulsar timing array cross correlations through theoretical uncertainty [CL]

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http://arxiv.org/abs/2304.07040


Incredible progress on the theoretical uncertainty of the spatial correlations of the stochastic gravitational wave (GW) background were recently made. However, it remains to realize the impact of this theoretical uncertainty on PTA cross correlations analysis. This paper pushes forward in this direction, as a proof–of–principle: showing the potential role that theoretical uncertainty has on unburying the stochastic GW background signal in noisy PTA cross correlation measurements. We consider both a mock data set and the noise–marginalized 12.5 years NANOGrav spatial correlation measurements, and find optimistic conclusions regardless of the physical content of the GW background and the nature of the noise in the data. Very briefly, we show through various cases a modest, but profound result that looking out for a stochastic signal is better when two of its moments are utilized. Or, in terms of GWs, we show that the theoretical uncertainty can play a substantial role in the hunt for the stochastic GW background.

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R. Bernardo and K. Ng
Mon, 17 Apr 23
9/51

Comments: 7 pages + refs, 3 figures, comments welcome

Effective Field Theories for Dark Matter Pairs in the Early Universe [CL]

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http://arxiv.org/abs/2304.07180


In this conference paper, we consider effective field theories of non-relativistic dark matter particles interacting with a light force mediator in the early expanding universe. We present a general framework, where to account in a systematic way for the relevant processes that may affect the dynamics during thermal freeze-out. In the temperature regime where near-threshold effects, most notably the formation of bound states and Sommerfeld enhancement, have a large impact on the dark matter relic density, we scrutinize possible contributions from higher excited states and radiative corrections in the annihilations and decays of dark-matter pairs.

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S. Biondini, N. Brambilla, G. Qerimi, et. al.
Mon, 17 Apr 23
21/51

Comments: Discussion about hierarchies of scales improved with respect to the published version in the conference proceedings. 4 pages, 2 figures, conference proceeding of “NuDM-2022”

Parity violating scalar-tensor model in teleparallel gravity and its cosmological application [CL]

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http://arxiv.org/abs/2304.07138


The parity violating model based on teleparallel gravity is a competitive scheme for parity violating gravity, which has been preliminary studied in the literature. To further investigate the parity violating model in teleparallel gravity, in this paper, we construct all independent parity-odd terms that are quadratic in torsion tensor and coupled to a scalar field in a way without higher-order derivatives. Using these parity-odd terms, we formulate a general parity violating scalar-tensor model in teleparallel gravity and obtain its equations of motion. To explore potentially viable models within the general model, we investigate the cosmological application of a submodel of the general model in which terms above the second power of torsion are eliminated. We focus on analyzing cosmological perturbations and identify the conditions that preserve the parity violating signal of gravitational waves at linear order while avoiding the ghost instability.

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H. Rao and D. Zhao
Mon, 17 Apr 23
33/51

Comments: 17 pages. arXiv admin note: text overlap with arXiv:2201.02357, arXiv:2301.02847

CAPP Axion Search Experiments with Quantum Noise Limited Amplifiers [CL]

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http://arxiv.org/abs/2304.07222


The axion is expected to solve the strong CP problem of quantum chromodynamics and is one of the leading candidates for dark matter. CAPP in South Korea has several axion search experiments based on cavity haloscopes in the frequency range of 1-6 GHz. The main effort focuses on operation of the experiments with the highest possible sensitivity. It requires maintenance of the haloscopes at the lowest physical temperature in the range of mK and usage of low noise components to amplify the weak axion signal. We report development and operation of low noise amplifiers for 5 haloscope experiments targeting at different frequency ranges. The amplifiers show noise temperatures approaching the quantum limit.

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S. Uchaikin, B. Ivanov, J. Kim, et. al.
Mon, 17 Apr 23
40/51

Comments: 6 pages, 7 figures, 29th International Conference on Low Temperature Physics, August 18-24, 2022, Sapporo, Japan

Inelastic Freeze-in [CL]

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http://arxiv.org/abs/2304.06072


Dark matter (DM) could be a nonthermal relic that freezes in from extremely weak, sub-Hubble annihilation and decay of Standard Model (SM) particles. The case of Dirac DM freezing in via a dark photon mediator is a well-studied benchmark for DM direct detection experiments. Here, we extend prior work to take into account the possibility that DM is pseudo-Dirac with a small mass splitting. If the mass splitting is greater than twice the electron mass but less than the dark photon mass, there will be distinct cosmological signatures. The excited state $\chi_2$ is initially produced in equal abundance to the ground state $\chi_1$. Subsequently, the excited state population decays at relatively late cosmological times, primarily via the three-body process $\chi_2 \rightarrow \chi_1 e^+ e^-$. This process injects energetic electrons into the ambient environment, providing observable signatures involving Big Bang nucleosynthesis, cosmic microwave background spectral distortions and anisotropies, and the Lyman-$\alpha$ forest. Furthermore, the ground state particles that are populated from the three-body decay receive a velocity kick, with implications for DM clustering on small scales. We find that cosmological probes and accelerator experiments are highly complementary, with future coverage of much of the parameter space of the model.

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S. Heeba, T. Lin and K. Schutz
Fri, 14 Apr 23
5/64

Comments: 15 pages, 6 figures + 1 secret doodle, comments welcome

Prospects for detecting anisotropies and polarization of the stochastic gravitational wave background with ground-based detectors [CL]

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http://arxiv.org/abs/2304.06640


We build an analytical framework to study the observability of anisotropies and a net chiral polarization of the Stochastic Gravitational Wave Background (SGWB) with a generic network of ground-based detectors. We apply this formalism to perform a Fisher forecast of the performance of a network consisting of the current interferometers (LIGO, Virgo and KAGRA) and planned third-generation ones, such as the Einstein Telescope and Cosmic Explorer. Our results yield limits on the observability of anisotropic modes, spanning across noise- and signal-dominated regimes. We find that if the isotropic component of the SGWB has an amplitude close to the current limit, third-generation interferometers with an observation time of $10$ years can measure multipoles (in a spherical harmonic expansion) up to $\ell = 8$ with ${\cal O }\left( 10^{-3} – 10^{-2} \right)$ accuracy relative to the isotropic component, and an ${\cal O }\left( 10^{-3} \right)$ amount of net polarization. For weaker signals, the accuracy worsens as roughly the inverse of the SGWB amplitude.

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G. Mentasti, C. Contaldi and M. Peloso
Fri, 14 Apr 23
9/64

Comments: 40 pages, 7 figures, prepared for submission to JCAP

Stability of relativistic tidal response against small potential modification [CL]

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http://arxiv.org/abs/2304.04551


The tidal response of compact objects in an inspiraling binary system is measured by a set of tidal Love and dissipation numbers imprinted in the gravitational waveforms. While a four-dimensional black hole in vacuum within General Relativity has vanishing Love numbers, a black hole in alternative theories of gravity can acquire non-vanishing Love numbers. The dissipation numbers may quantify Planckian corrections at the horizon scale. These properties will allow a test of classical theories of gravity in the strong-field regime with gravitational-wave observation. Since black holes are not in the exact vacuum environment in astrophysical situations, the following question arises: can the environment affect the tidal response? In this paper, we investigate the stability of the tidal response of a Schwarzschild black hole for frequency-dependent tidal-field perturbations against a small modification of the background. Our analysis relies on the scattering theory, which overcomes difficulties in defining the relativistic tidal Love numbers. The tidal Love and dissipation numbers can be extracted from the phase shift of sufficiently low-frequency scattering waves. We show that the tidal Love numbers are sensitive to the property of the modification. Therefore, we need careful consideration of the environment around the black hole in assessing the deviation of the underlying theory of gravity from General Relativity with the Love numbers. The modification has less impact on the dissipation numbers, indicating that quantifying the existence of the event horizon with them is not spoiled. We also demonstrate that in a composite system, i.e., a compact object with environmental effects, the Love and dissipation numbers are approximately determined by the sum of the numbers of each component.

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T. Katagiri, H. Nakano and K. Omukai
Fri, 14 Apr 23
23/64

Comments: 45 pages, 23 figures

Chiral magnetohydrodynamics with zero total chirality [CL]

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http://arxiv.org/abs/2304.06612


We study the evolution of magnetic fields coupled with chiral fermion asymmetry in the framework of chiral magnetohydrodynamics with zero initial total chirality. The initial magnetic field has a turbulent spectrum peaking at a certain characteristic scale and is fully helical with positive helicity. The initial chiral chemical potential is spatially uniform and negative. We consider two opposite cases where the ratio of the length scale of the chiral plasma instability (CPI) to the characteristic scale of the turbulence is smaller and larger than unity. These initial conditions might be realized in cosmological models such as certain types of axion inflation. The magnetic field and chiral chemical potential evolve with inverse cascading in such a way that the magnetic helicity and chirality cancel each other at all times. The CPI time scale is found to determine mainly the time when the magnetic helicity spectrum attains negative values at high wave numbers. The turnover time of the energy-carrying eddies, on the other hand, determines the time when the peak of the spectrum starts to shift to smaller wave numbers via an inverse cascade. The onset of helicity decay is determined by the time when the chiral magnetic effect becomes efficient at the peak of the initial magnetic energy spectrum. When spin flipping is important, the chiral chemical potential vanishes and the magnetic helicity becomes constant, which leads to a faster increase of the correlation length, as expected from magnetic helicity conservation. This also happens when the initial total chirality is imbalanced. Our findings have important implications for baryogenesis after axion inflation.

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A. Brandenburg, K. Kamada, K. Mukaida, et. al.
Fri, 14 Apr 23
42/64

Comments: 21 pages, 20 figures, 4 tables

Fine tuning of rainbow gravity functions and Klein-Gordon particles in cosmic string rainbow gravity spacetime [CL]

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http://arxiv.org/abs/2304.06546


We argue that, as long as relativistic quantum particles are in point, the variable $y=E/E_p$ of the rainbow functions pair $g_{{0}} (y)$ and $g{{1}} (y)$ should be fine tuned into $y=|E|/E_p$, where $E_p$ is the Planck’s energy scale. Otherwise, the rainbow functions will be only successful to describe the rainbow gravity effect on relativistic quantum particles and the anti-particles will be left unfortunate. Under such fine tuning, we consider Klein-Gordon (KG) particles in cosmic string rainbow gravity spacetime in a non-uniform magnetic field (i.e., $\mathbf{B}=\mathbf{\nabla }\times \mathbf{A}=\frac{3}{2}B{\circ }r\,\hat{z}$ ). Then we consider KG-particles in cosmic string rainbow gravity spacetime in a uniform magnetic field (i.e., $\mathbf{B}=\mathbf{\nabla }\times \mathbf{A}=\frac{1}{2}B_{\circ }\,\hat{z}$ ). Whilst the former effectively yields KG-oscillators, the later effectively yields KG-Coulombic particles. We report on the effects of rainbow gravity on both KG-oscillators and Coulombic particles using four pairs of rainbow functions: (i) $% g_{{0}}\left( y\right) =1$, $g{{1}}\left( y\right) =\sqrt{1-\epsilon y^{2}% }$, (ii) $g{{0}}\left( y\right) =1$, $g{{1}}\left( y\right) =\sqrt{% 1-\epsilon y}$, (iii) $g{{0}}\left( y\right) =g{{1}}\left( y\right) =\left( 1-\epsilon y\right) ^{-1}$, and (iv) $g{{0}}\left( y\right) =\left( e^{\epsilon y}-1\right) /\epsilon y$, $g{_{1}}\left( y\right) =1$, where $y=|E|/E_p$ and $\epsilon$ is the rainbow parameter. It is interesting to report that, all KG particles’ and anti-particles’ energies are symmetric about $E=0$ value (a natural relativistic quantum mechanical tendency), and a phenomenon of energy states to fly away and disappear from the spectrum is observed for the rainbow functions pair (iii) at $\gamma=\epsilon m/E_p=1$.

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O. Mustafa
Fri, 14 Apr 23
46/64

Comments: 15 pages, 7 figures. arXiv admin note: substantial text overlap with arXiv:2301.05464, arXiv:2301.12370

Stellar Signals of a Baryon-Number-Violating Long-Range Force [CL]

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http://arxiv.org/abs/2304.06071


We entertain the novel possibility that long range forces may lead to violations of accidental symmetries, in particular baryon number. Employing an ultralight scalar, with a mass $\ll$ eV, we illustrate that this scenario can lead to vastly disparate nucleon lifetimes, in different astronomical objects. Such a long range interaction can yield a number of potentially observable effects, such as a flux of neutrinos at $\gtrsim 10$ MeV from the Sun and heating of old neutron stars. We examine the prospects for constraining this scenario, with current and future astrophysical data, and find that neutron star heating provides the strongest present and near term bounds. Simple extensions of our setup allow for the ultralight scalar to constitute the dark matter of the Universe. This suggests that matter-enhanced baryon number violation can be a signal of ultralight dark matter, which has apparently been overlooked, so far.

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H. Davoudiasl
Fri, 14 Apr 23
53/64

Comments: 7 pages, 1 figure

Constraining low-scale dark phase transitions with cosmological observations [CL]

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http://arxiv.org/abs/2304.06576


We investigate the effects of the low-scale cosmological first-order phase transitions on the neutrino decoupling and constrain the PT parameters with the cosmological observations of big bang nucleosynthesis and cosmic microwave background. We consider the phase transitions that occur at the MeV-scale which can produce stochastic gravitational wave background to be probed by pulsar timing array experiments. We find that the phase transition can modify the effective number of neutrinos and the primordial nucleosynthesis. In turn, the cosmological observations can exclude slow and strong phase transitions around the MeV scale.

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S. Deng and L. Bian
Fri, 14 Apr 23
54/64

Comments: 6 pages, 5 figures

Priors for symbolic regression [CL]

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http://arxiv.org/abs/2304.06333


When choosing between competing symbolic models for a data set, a human will naturally prefer the “simpler” expression or the one which more closely resembles equations previously seen in a similar context. This suggests a non-uniform prior on functions, which is, however, rarely considered within a symbolic regression (SR) framework. In this paper we develop methods to incorporate detailed prior information on both functions and their parameters into SR. Our prior on the structure of a function is based on a $n$-gram language model, which is sensitive to the arrangement of operators relative to one another in addition to the frequency of occurrence of each operator. We also develop a formalism based on the Fractional Bayes Factor to treat numerical parameter priors in such a way that models may be fairly compared though the Bayesian evidence, and explicitly compare Bayesian, Minimum Description Length and heuristic methods for model selection. We demonstrate the performance of our priors relative to literature standards on benchmarks and a real-world dataset from the field of cosmology.

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D. Bartlett, H. Desmond and P. Ferreira
Fri, 14 Apr 23
62/64

Comments: 8+2 pages, 2 figures. Submitted to The Genetic and Evolutionary Computation Conference (GECCO) 2023 Workshop on Symbolic Regression

Multi-brane cosmology [CL]

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http://arxiv.org/abs/2304.05586


5D warped extra dimension models with multiple 3-branes can naturally realize multiple hierarchical mass scales which are ubiquitous in physics beyond the Standard Model. We discuss cosmological consequences of such multi-brane models with stabilized radions. It is confirmed that for temperatures below the scale of the IR brane at the end of the extra dimension, we recover the ordinary expansion of the Universe, with the Hubble expansion rate determined by sum of the physical energy densities on all 3-branes where they are localized. In addition, we explore the cosmology for temperatures above the scales of the intermediate and IR branes where the Universe is described by a spacetime with the 3-branes replaced by an event horizon. As the temperature of the Universe cools down, phase transitions are expected to take place, and the intermediate and IR branes come out from behind the event horizon. The Goldberger-Wise mechanism for radion stabilization has a well-known problem of having a supercooled phase transition, which typically does not get completed in time. This problem is even more severe when an intermediate brane is introduced, whose scale is well above TeV, as the corresponding Hubble rate is much larger. We circumvent the problem by employing an alternative mechanism for radion stabilization with dark Yang-Mills fields, which prevents a long supercooling epoch, but still allows the strong first order phase transitions. As a result, the phase transitions in our multi-brane Universe predict a stochastic gravitational wave background with a unique multi-peak signature, which is within the sensitivity reach of future space-based gravitational wave observers. We also show that there are $N-1$ radions for an $N$ 3-brane set-up, unlike a recent claim that there exists only one radion.

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S. Girmohanta, S. Lee, Y. Nakai, et. al.
Thu, 13 Apr 23
1/59

Comments: 34 pages, 6 figures

Loop Quantum Cosmology: Physics of Singularity Resolution and its Implications [CL]

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http://arxiv.org/abs/2304.05426


The occurrence of singularities where spacetime curvature becomes infinite and geodesic evolution breaks down are inevitable events in classical general relativity (GR) unless one chooses an exotic matter violating weak energy condition. These singularities show up in various physical processes, such as the gravitational collapse, the birth of the universe in the standard cosmology as well as the classical solutions of the black hole spacetimes. In the last two decades, a rigorous understanding of the dynamics of quantum spacetime and the way it resolves singularities has been achieved in loop quantum cosmology (LQC) which applies the concepts and techniques of loop quantum gravity to the symmetry reduced cosmological spacetimes. Due to the fundamental discreteness of quantum geometry derived from the quantum theory, the big bang singularity has been robustly shown to be replaced by a big bounce. Strong curvature singularities intrinsic in the classical cosmology are generically resolved for a variety of cosmological spacetimes including anisotropic models and polarized Gowdy models. Using effective spacetime description the LQC universe also provides an ultra-violet complete description of the classical inflationary scenario as well as its alternatives such as the ekpyrotic and matter bounce scenarios. In this chapter we provide a summary of singularity resolution and its physical implications for various isotropic and anisotropic cosmological spacetimes in LQC and analyze robustness of results through variant models originating from different quantization prescriptions.

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B. Li and P. Singh
Thu, 13 Apr 23
28/59

Comments: 48 pages, 3 figures. Invited chapter to appear in the “Handbook of Quantum Gravity”, edited by Cosimo Bambi, Leonardo Modesto and Ilya Shapiro, Springer (2023)

Complexity and simplicity of self-gravitating fluids [CL]

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http://arxiv.org/abs/2304.05870


We review a recently proposed definition of complexity of the structure of self–gravitating fluids \cite{ch1}, and the criterium to define the simplest mode of their evolution. We analyze the origin of these concepts and their possible applications in the study of gravitation collapse. We start by considering the static spherically symmetric case, extending next the study to static axially symmetric case. Afterward we consider the non–static spherically symmetric case. Two possible modes of evolution are proposed to be the simplest one. One is the homologous conditio,, however, as was shown later on, it may be useful to relax this last condition to enlarge the set of possible solutions, by adopting the so-called quasi-homologous condition. As another example of symmetry, we consider fluids endowed with hyperbolical symmetry. Exact solutions for static fluid distributions satisfying the condition of minimal complexity are presented.. An extension of the complexity factor to the vacuum solutions of the Einstein equations represented by the Bondi metric is discussed. A complexity hierarchy is established in this case, ranging from the Minkowski spacetime (the simplest one) to gravitationally radiating systems (the most complex). Finally we propose a list of questions which, we believe, deserve to be treated in the future

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L. Herrera
Thu, 13 Apr 23
35/59

Comments: 30 pages Latex (Revtex-4). Invited chapter for the edited book New Frontiers in Gravitational Collapse and Spacetime Singularities (Eds. P. Joshi and D. Malafarina, Springer Singapore), expected in 2023

Self-resonant Dark Matter [CL]

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http://arxiv.org/abs/2304.05942


We present a review on the self-resonant dark matter scenarios where multiple components of dark matter give rise to a resonant condition in the $u$-channel diagrams for their comparable masses. In this case, there is no need of lighter mediators for enhancing the self-scattering and annihilation cross sections for dark matter. We discuss the velocity-dependent self-scattering for the small-scale problems, the relic density of self-resonant dark matter, and the observable signatures in indirect and detection experiments.

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H. Lee
Thu, 13 Apr 23
39/59

Comments: 7 pages, 4 figures. To appear in the proceedings for the 19th Rencontres du Vietnam Theory Meeting Experiment (TMEX) 2023

Galactic ChitChat: Using Large Language Models to Converse with Astronomy Literature [CL]

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http://arxiv.org/abs/2304.05406


We demonstrate the potential of the state-of-the-art OpenAI GPT-4 large language model to engage in meaningful interactions with Astronomy papers using in-context prompting. To optimize for efficiency, we employ a distillation technique that effectively reduces the size of the original input paper by 50\%, while maintaining the paragraph structure and overall semantic integrity. We then explore the model’s responses using a multi-document context (ten distilled documents). Our findings indicate that GPT-4 excels in the multi-document domain, providing detailed answers contextualized within the framework of related research findings. Our results showcase the potential of large language models for the astronomical community, offering a promising avenue for further exploration, particularly the possibility of utilizing the models for hypothesis generation.

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I. Ciucă and Y. Ting
Thu, 13 Apr 23
42/59

Comments: 3 pages, submitted to RNAAS, comments very welcome from the community

Revisiting Affleck-Dine Leptogenesis with light sleptons [CL]

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http://arxiv.org/abs/2304.05614


We revisit the Affleck-Dine leptogenesis via the $L H_u$ flat direction with a light slepton field. Although the light slepton field is favored in low-energy SUSY phenomenologies, such as the muon $g-2$ anomaly and bino-slepton coannihilation, it may cause a problem in the Affleck-Dine leptogenesis: it may create an unwanted charge-breaking vacuum in the Affleck-Dine field potential so that the Affleck-Dine field is trapped during the course of leptogenesis. We investigate the conditions under which such an unwanted vacuum exists and clarify that both thermal and quantum corrections are important for the (temporal) disappearance of the charge-breaking minimum. We also confirm that if the charge-breaking vacuum disappears due to the thermal or quantum correction, the correct baryon asymmetry can be produced while avoiding the cosmological gravitino problem.

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K. Enomoto, K. Hamaguchi, K. Kamada, et. al.
Thu, 13 Apr 23
45/59

Comments: 12 pages, 2 figures

Building an Equation of State Density Ladder [CL]

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http://arxiv.org/abs/2304.05441


The confluence of major theoretical, experimental, and observational advances are providing a unique perspective on the equation of state of dense neutron-rich matter — particularly its symmetry energy — and its imprint on the mass-radius relation for neutron stars. In this contribution we organize these developments in an equation of state density ladder. Of particular relevance to this discussion is the impact of the various rungs on the equation of state and the identification of possible discrepancies among the various methods. A preliminary analysis identifies a possible tension between laboratory measurements and gravitational-wave detections that could indicate the emergence of a phase transition in the stellar core.

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M. Salinas and J. Piekarewicz
Thu, 13 Apr 23
54/59

Comments: N/A

Efficient multi-timescale dynamics of precessing black-hole binaries [CL]

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http://arxiv.org/abs/2304.04801


We present analytical and numerical progress on black-hole binary spin precession at second post-Newtonian order using multi-timescale methods. In addition to the commonly used effective spin which acts as a constant of motion, we exploit the weighted spin difference and show that such reparametrization cures the coordinate singularity that affected the previous formulation for the case of equal-mass binaries. The dynamics on the precession timescale is written down in closed form in both coprecessing and inertial frames. Radiation-reaction can then be introduced in a quasi-adiabatic fashion such that, at least for binaries on quasi-circular orbits, gravitational inspirals reduce to solving a single ordinary differential equation. We provide a broad review of the resulting phenomenology and re-write the relevant physics in terms of the newly adopted parametrization. This includes the spin-orbit resonances, the up-down instability, spin propagation at past time infinity, and new precession estimators to be used in gravitational-wave astronomy. Our findings are implemented in version 2 of the public Python module PRECESSION. Performing a precession-averaged post-Newtonian evolution from/to arbitrarily large separation takes $\lesssim 0.1$ s on a single off-the-shelf processor. This allows for a wide variety of applications including propagating gravitational-wave posterior samples as well as population-synthesis predictions of astrophysical nature.

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D. Gerosa, G. Fumagalli, M. Mould, et. al.
Wed, 12 Apr 23
1/45

Comments: Code available at this https URL

Updated Constraints and Future Prospects on Majoron Dark Matter [CL]

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http://arxiv.org/abs/2304.04430


Majorons are (pseudo-)Nambu-Goldstone bosons associated with lepton number symmetry breaking due to the Majorana mass term of neutrinos introduced in the seesaw mechanism. They are good dark matter candidates since their lifetime is suppressed by the lepton number breaking scale. We update constraints and discuss future prospects on majoron dark matter in the singlet majoron models based on neutrino, gamma-ray, and cosmic-ray telescopes in the mass region of MeV–10 TeV.

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K. Akita and M. Niibo
Wed, 12 Apr 23
3/45

Comments: 25 pages, 6 figures, 3 tables

Solving the domain wall problem with first-order phase transition [CL]

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http://arxiv.org/abs/2304.05220


Domain wall networks are two-dimensional topological defects generally predicted in many beyond standard model physics. In this Letter, we propose to solve the domain wall problem with the first-order phase transition. We numerically study the phase transition dynamics, and for the first time show that the domain walls reached scaling regime can be diluted through the interaction with vacuum bubbles during the first-order phase transition. We find that the amplitude of the gravitational waves produced by the second-stage first-order phase transition is several orders higher than that from the domain walls evolution in the scaling regime. The scale of the first-order phase transition that dilute the domain walls can be probed through gravitational waves detection.

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Y. Li, L. Bian and Y. Jia
Wed, 12 Apr 23
18/45

Comments: 6+7 pages, 6+6 figures

Primordial Black Hole Archaeology with Gravitational Waves from Cosmic Strings [CL]

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http://arxiv.org/abs/2304.04793


Light primordial black holes (PBHs) with masses smaller than $10^9$ g ($10^{-24} M_\odot$) evaporate before the onset of Big-Bang nucleosynthesis, rendering their detection rather challenging. If efficiently produced, they may have dominated the universe energy density. We study how such an early matter-dominated era can be probed successfully using gravitational waves (GW) emitted by local and global cosmic strings. While previous studies showed that a matter era generates a single-step suppression of the GW spectrum, we instead find a “double-step” suppression for local-string GW whose spectral shape provides information on the duration of the matter era. The presence of the two steps in the GW spectrum originates from GW being produced through two events separated in time: loop formation and loop decay, taking place either before or after the matter era. The second step – called the “knee” – is a novel feature which is universal to any early matter-dominated era and is not only specific to PBHs. Detecting GWs from cosmic strings with LISA, ET, or BBO would set constraints on PBHs with masses between $10^6$ and $10^9$ g for local strings with tension $G\mu = 10^{-11}$, and PBHs masses between $10^4$ and $10^9$ g for global strings with symmetry-breaking scale $\eta = 10^{15}~\mathrm{GeV}$. Effects from the spin of PBHs are discussed.

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A. Ghoshal, Y. Gouttenoire, L. Heurtier, et. al.
Wed, 12 Apr 23
39/45

Comments: 21 pages, 9 figures (main text without references) + 4 pages, 3 figures (appendices)

Strong Gravitational Lensing of Gravitational Waves with TianQin [CL]

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http://arxiv.org/abs/2304.04800


When gravitational waves pass by a massive object on its way to the Earth, strong gravitational lensing effect will happen. Thus the GW signal will be amplified, deflected, and delayed in time. Through analysing the lensed GW waveform, physical properties of the lens can be inferred. On the other hand, neglecting lensing effects in the analysis of GW data may induce systematic errors in the estimating of source parameters. As a space-borne GW detector, TianQin will be launched in the 2030s. It is expected to detect dozens of MBHBs merger as far as z = 15, and thus will have high probability to detect at least one lensed event during the mission lifetime. In this article, we discuss the capability of TianQin to detect lensed MBHBs signals. Three lens models are considered in this work: the point mass model, the SIS model, and the NFW model. The sensitive frequency band for space-borne GW detectors is around milli-hertz, and the corresponding GW wavelength could be comparable to the lens gravitational length scale, which requires us to account for wave diffraction effects. In calculating lensed waveforms, we adopt the approximation of geometric optics at high frequencies to accelerate computation, while precisely evaluate the diffraction integral at low frequencies. Through a Fisher analysis, we analyse the accuracy to estimate the lens parameters. We find that the accuracy can reach to the level of 10^-3 for the mass of point mass and SIS lens, and to the level of 10^-5 for the density of NFW lens. We also assess the impact on the accurate of estimating the source parameters, and find that the improvement of the accuracy is dominated by the increasing of SNR.

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X. Lin, J. Zhang, L. Dai, et. al.
Wed, 12 Apr 23
45/45

Comments: 12 pages, 8 figures

Efficient large-scale, targeted gravitational-wave probes of supermassive black-hole binaries [CL]

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http://arxiv.org/abs/2304.03786


Supermassive black hole binaries are promising sources of low-frequency gravitational waves (GWs) and bright electromagnetic emission. Pulsar timing array searches for resolved binaries are complex and computationally expensive and so far limited to only a few sources. We present an efficient approximation that empowers large-scale targeted multi-messenger searches by neglecting GW signal components from the pulsar term. This Earth-term approximation provides similar constraints on the total mass and GW frequency of the binary, yet is $>100$ times more efficient.

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M. Charisi, S. Taylor, C. Witt, et. al.
Tue, 11 Apr 23
14/63

Comments: Comments welcome

There and back again: Solar cycle effects in future measurements of low-energy atmospheric neutrinos [CL]

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http://arxiv.org/abs/2304.04689


We study the impact of time-dependent solar cycles in the atmospheric neutrino rate at DUNE and Hyper-Kamiokande (HK), focusing in particular on the flux below 1 GeV. Including the effect of neutrino oscillations for the upward-going component that travels through the Earth, we find that across the solar cycle the amplitude of time variation is about $\pm5\%$ at DUNE, and $\pm 1\%$ at HK. At DUNE, the ratio of up/down-going events ranges from 0.45 to 0.85, while at HK, it ranges from 0.75 to 1.5. Over the 11-year solar cycle, we find that the estimated statistical significance for observing time modulation of atmospheric neutrinos is $4.8\sigma$ for DUNE and $2.0\sigma$ for HK. Flux measurements at both DUNE and HK will be important for understanding systematics in the low-energy atmospheric flux as well as for understanding the effect of oscillations in low-energy atmospheric neutrinos.

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K. Kelly, P. Machado, N. Mishra, et. al.
Tue, 11 Apr 23
15/63

Comments: 6 pages (including one appendix), 5 figures. Comments welcome

Conservative limits on the electric charge of Sgr A* in the Reissner-Nordstrom metric [CL]

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http://arxiv.org/abs/2304.04313


In General Relativity, the gravitational field of an electrically charged, non-rotating, spherically symmetric body is described by the Reissner-Nordstrom (RN) metric. In the naked-singularity regime, a general property of this metric is the existence of a radius, known as the zero-gravity radius, where a test particle would remain at rest. As a consequence of repulsive gravity there is no circular orbit inside this radius. A part of any quasi-stable structure must necessarily lie outside of it. Assuming the compact source Sgr A* at the galactic center may be a naked singularity in RN metric, we provide constraints on the electric charge-to-mass ratio Q/M based on different observations. The compari12 son between the Event Horizon Telescope (EHT) observations and the space-time zero-gravity radius provides the most conservative limit on the charge of Sgr A* to be Q/M < 2.32. Therefore, a charged naked singularity respecting this charge-to-mass constraint is indeed consistent with the current EHT observations.

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R. Mishra and R. Vieira
Tue, 11 Apr 23
16/63

Comments: 6 pages, 3 figures

Polarized images of charged particles in vortical motions around a magnetized Kerr black hole [CL]

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http://arxiv.org/abs/2304.03642


In this work, we study the images of a Kerr black hole (BH) immersed in uniform magnetic fields, illuminated by the synchrotron radiation of charged particles in the jet. We particularly focus on the spontaneously vortical motions (SVMs) of charged particles in the jet region and investigate the polarized images of electromagnetic radiations from the trajectories along SVMs. We notice that there is a critical value $\omega_c$ for charged particle released at a given initial position and subjected an outward force, and once $|qB_0/m|=|\omega_B|>|\omega_c|$ charged particles can move along SVMs in the jet region. We obtain the polarized images of the electromagnetic radiations from the trajectories along SVMs. Our simplified model suggests that the SVM radiations can act as the light source to illuminate the BH and form a photon ring structure.

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Z. Zhang, Y. Hou, Z. Hu, et. al.
Tue, 11 Apr 23
20/63

Comments: 24 pages, 8 figures

A Solar Investigation of Multicomponent Dark Matter [CL]

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http://arxiv.org/abs/2304.04721


If multiple thermal weakly interacting massive particle (WIMP) dark matter candidates exist, then their capture and annihilation dynamics inside a massive stars such as Sun could change from conventional method of study. With a simple correction to time evolution of dark matter (DM) number abundance inside the Sun for multiple dark matter candidates, significant changes in DM annihilation flux depending on annihilation, direct detection cross-section, internal conversion and their contribution to relic abundance are reported in present work.

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A. Banik
Tue, 11 Apr 23
23/63

Comments: 12 pages, 8 figures

Perils of Towers in the Swamp: Dark Dimensions and the Robustness of Effective Field Theories [CL]

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http://arxiv.org/abs/2304.03902


Recently there has been an interesting revival of the idea to use large extra dimensions to address the dark energy problem, exploiting the (true) observation that towers of states with masses split, by $M^2_N = f(N) m^2,$ with $f$ an unbounded function of the integer $N$, sometimes contribute to the vacuum energy only an amount of order $m^D$ in $D$ dimensions. It has been argued that this fact is a consequence of swampland conjectures and may require a departure from Effective Field Theory (EFT) reasoning. We test this claim with calculations for Casimir energies in extra dimensions. We show why the domain of validity for EFTs ensures that the tower spacing scale $m$ is always an upper bound on the UV scale for the lower-energy effective theory; use of an EFT with a cutoff part way up a tower is not a controlled approximation. We highlight the role played by the sometimes-suppressed contributions from towers in extra-dimensional approaches to the cosmological constant problem, old and new, and point out difficulties encountered in exploiting it. We compare recent swampland realizations of these arguments with earlier approaches using standard EFT examples, discussing successes and limitations of both.

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C. Burgess and F. Quevedo
Tue, 11 Apr 23
28/63

Comments: 11 pages, 1 figure

Aspects of Everpresent $Λ$ (I): A Fluctuating Cosmological Constant from Spacetime Discreteness [CL]

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http://arxiv.org/abs/2304.03819


We provide a comprehensive discussion of the Everpresent $\Lambda$ cosmological model arising from fundamental principles in causal set theory and unimodular gravity. In this framework the value of the cosmological constant ($\Lambda$) fluctuates, in magnitude and in sign, over cosmic history. At each epoch, $\Lambda$ stays statistically close to the inverse square root of the spacetime volume. Since the latter is of the order of $H^2$ today, this provides a way out of the cosmological constant puzzle without fine tuning. Our discussion includes a review of what is known about the topic as well as new motivations and insights supplementing the original arguments. We also study features of a phenomenological implementation of this model, and investigate the statistics of simulations based on it. Our results show that while the observed values of $H_0$ and $\Omega_\Lambda^0$ are not typical outcomes of the model, they can be achieved through a modest number of simulations. We also confirm some expected features of $\Lambda$ based on this model, such as the fact that it stays statistically close to the value of the total ambient energy density (be it matter or radiation dominated), and that it is likely to change sign roughly every Hubble timescale.

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S. Das, A. Nasiri and Y. Yazdi
Tue, 11 Apr 23
31/63

Comments: 28 pages, 10 figures

Variation of the quadrupole hyperfine structure and nuclear radius due to an interaction with scalar and axion dark matter [CL]

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http://arxiv.org/abs/2304.04469


Atomic spectroscopy is used to search for the space-time variation of fundamental constants which may be due to an interaction with scalar and pseudo-scalar (axion) dark matter. In this letter, we study the effects which are produced by the variation of the nuclear radius and electric quadrupole moment. The sensitivity of the electric quadrupole hyperfine structure to both the variation of the quark mass and the effects of dark matter exceeds that of the magnetic hyperfine structure by 1-2 orders of magnitude. Therefore, the measurement of the variation of the ratio of the electric quadrupole and magnetic dipole hyperfine constants is proposed. The sensitivity of the optical clock transitions in the Yb$^+$ ion to the variation of the nuclear radius allows us to extract, from experimental data, limits on the variation of the hadron and quark masses, the QCD parameter $\theta$ and the interaction with axion and scalar dark matter.

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V. Flambaum and A. Mansour
Tue, 11 Apr 23
52/63

Comments: N/A

A viable form of the metric Teleparallel F(T) theory of gravity [CL]

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http://arxiv.org/abs/2304.04180


Unlike F(R) gravity, pure metric F(T) gravity in the vacuum dominated era, ends up with an imaginary action and is therefore not feasible. This eerie situation may only be circumvented by associating a scalar field, which can also drive inflation in the very early universe. We show that, despite diverse claims, F(T) theory admits Noether symmetry only in the pressure-less dust era in the form F(T) proportional to the nth power of T, n being odd integers. A suitable form of F(T), admitting a viable Friedmann-like radiation dominated era, together with early deceleration and late-time accelerated expansion in the pressure-less dust era, has been proposed.

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M. Chakrabortty, N. Sk and A. Sanyal
Tue, 11 Apr 23
57/63

Comments: 12 pages, 0 figures

MSSM-inflation revisited: Towards a coherent description of high-energy physics and cosmology [CL]

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http://arxiv.org/abs/2304.04534


The aim of this paper is to highlight the challenges and potential gains surrounding a coherent description of physics from the high-energy scales of inflation down to the lower energy scales probed in particle-physics experiments. As an example, we revisit the way inflation can be realised within an effective Minimal Supersymmetric Standard Model (eMSSM), in which the $LLe$ and $udd$ flat directions are lifted by the combined effect of soft-supersymmetric-breaking masses already present in the MSSM, together with the addition of effective non-renormalizable operators. We clarify some features of the model and address the question of the one-loop Renormalization Group improvement of the inflationary potential, discussing its impact on the fine-tuning of the model. We also compare the parameter space that is compatible with current observations (in particular the amplitude, $A_{\scriptscriptstyle{\mathrm{S}}}$, and the spectral index, $n_{\scriptscriptstyle{\mathrm{S}}}$, of the primordial cosmological fluctuations) at tree level and at one loop, and discuss the role of reheating. Finally we perform combined fits of particle and cosmological observables (mainly $A_{\scriptscriptstyle{\mathrm{S}}}$, $n_{\scriptscriptstyle{\mathrm{S}}}$, the Higgs mass, and the cold-dark-matter energy density) with the one-loop inflationary potential applied to some examples of dark-matter annihilation channels (Higgs-funnel, Higgsinos and A-funnel), and discuss the status of the ensuing MSSM spectra with respect to the LHC searches.

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G. Weymann-Despres, S. Henrot-Versillé, G. Moultaka, et. al.
Tue, 11 Apr 23
62/63

Comments: 38 pages, 7 figures

Fine-structure transitions of Si and S induced by collisions with atomic hydrogen [CL]

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http://arxiv.org/abs/2304.02727


Using a quantum-mechanical close-coupling method, we calculate cross sections for fine structure excitation and relaxation of Si and S atoms in collisions with atomic hydrogen. Rate coefficients are calculated over a range of temperatures for astrophysical applications. We determine the temperature-dependent critical densities for the relaxation of Si and S in collisions with H and compare these to the critical densities for collisions with electrons. The present calculation should be useful in modeling environments exhibiting the [S i] 25 {\mu}m and [S i] 57 {\mu}m far-infrared emission lines or where cooling of S and Si by collisions with H are of interest.

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P. Yan and J. Babb
Mon, 10 Apr 23
5/36

Comments: Accepted for publication in MNRAS

Fast inference of binary merger properties using the information encoded in the gravitational-wave signal [CL]

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http://arxiv.org/abs/2304.03731


Using simple, intuitive arguments, we discuss the expected accuracy with which astrophysical parameters can be extracted from an observed gravitational wave signal. The observation of a chirp like signal in the data allows for measurement of the component masses and aligned spins, while measurement in three or more detectors enables good localization. The ability to measure additional features in the observed signal — the existence or absence of power in i) the second gravitational wave polarization, ii) higher gravitational wave multipoles or iii) spin-induced orbital precession — provide new information which can be used to significantly improve the accuracy of parameter measurement. We introduce the simple-pe algorithm which uses these methods to generate rapid parameter estimation results for binary mergers. We present results from a set of simulations, to illustrate the method, and compare results from simple-pe with measurements from full parameter estimation routines. The simple-pe routine is able to provide initial parameter estimates in a matter of CPU minutes, which could be used in real-time alerts and also as input to significantly accelerate detailed parameter estimation routines.

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S. Fairhurst, C. Hoy, R. Green, et. al.
Mon, 10 Apr 23
9/36

Comments: 33 pages, 15 figures

Non-thermal particle acceleration and power-law tails via relaxation to universal Lynden-Bell equilibria [CL]

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http://arxiv.org/abs/2304.03715


Collisionless and weakly collisional plasmas often exhibit non-thermal quasi-equilibria. Among these quasi-equilibria, distributions with power-law tails are ubiquitous. It is shown that the statistical-mechanical approach originally suggested by Lynden-Bell (1967) can easily recover such power-law tails. Moreover, we show that, despite the apparent diversity of Lynden-Bell equilibria, a generic form of the equilibrium distribution at high energies is a hard' power-law tail $\propto \varepsilon^{-2}$, where $\varepsilon$ is the particle energy. The shape of thecore’ of the distribution, located at low energies, retains some dependence on the initial condition but it is the tail (or `halo’) that contains most of the energy. Thus, a degree of universality exists in collisionless plasmas.

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R. Ewart, M. Nastac and A. Schekochihin
Mon, 10 Apr 23
23/36

Comments: 28 pages, 5 figures

Accelerating universe at the end of time [CL]

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http://arxiv.org/abs/2303.03418


We investigate whether an accelerating universe can be realized as an asymptotic late-time solution of FLRW-cosmology with multi-field multi-exponential potentials. Late-time cosmological solutions exhibit a universal behavior which enables us to bound the rate of time variation of the Hubble parameter. In string-theoretic realizations, if the dilaton remains a rolling field, our bound singles out a tension in achieving asymptotic late-time cosmic acceleration. Our findings go beyond previous no-go theorems in that they apply to arbitrary multi-exponential potentials and make no specific reference to vacuum or slow-roll solutions. We also show that if the late-time solution approaches a critical point of the dynamical system governing the cosmological evolution, the criterion for cosmic acceleration can be generally stated in terms of a directional derivative of the potential.

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G. Shiu, F. Tonioni and H. Tran
Mon, 10 Apr 23
30/36

Comments: 6 pages + appendix

Revisiting proton-proton fusion in chiral effective field theory [CL]

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http://arxiv.org/abs/2304.03327


We calculate the $S$-factor for proton-proton fusion using chiral effective field theory interactions and currents. By performing order-by-order calculations with a variety of chiral interactions that are regularized and calibrated in different ways, we assess the uncertainty in the $S$-factor from the truncation of the effective field theory expansion and from the sensitivity of the $S$-factor to the short-distance axial current determined from three- and four-nucleon observables. We find that $S(0)=(4.100\pm0.019\mathrm{(syst)}\pm0.013\mathrm{(stat)}\pm0.008(g_A))\times10^{-23}~\mathrm{MeV\,fm}^2\,,$ where the three uncertainties arise, respectively, from the truncation of the effective field theory expansion, use of the two-nucleon axial current fit to few-nucleon observables and variation of the axial coupling constant within the recommended range.

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B. Acharya, L. Marcucci and L. Platter
Mon, 10 Apr 23
31/36

Comments: N/A

Neutrino spin and flavor oscillations in gravitational fields [CL]

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http://arxiv.org/abs/2304.03622


We study spin and flavor oscillations of astrophysical neutrinos under the influence of external fields in curved spacetime. First, we consider spin oscillations in case of neutrinos gravitationally scattered off a rotating supermassive black hole surrounded by a thin magnetized accretion disk. We find that the gravitational interaction only does not result in the spin-flip of scattered ultrarelativistic neutrinos. Realistic magnetic fields lead to the significant reduction of the observed flux of neutrinos possessing reasonable magnetic moments. Second, we study neutrino flavor oscillations in stochastic gravitational waves (GWs). We derive the effective Hamiltonian for neutrinos interacting with a plane GW having an arbitrary polarization. Then, we consider stochastic GWs with arbitrary correlators of amplitudes. The equation for the density matrix for neutrino oscillations is solved analytically and the probabilities to detect certain neutrino flavors are derived. We find that the interaction of neutrinos, emitted by a core-collapsing supernova, with the stochastic GW background results in the several percent change of the neutrino fluxes. The observability of the predicted effects is discussed.

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M. Dvornikov
Mon, 10 Apr 23
32/36

Comments: 8 pages in LaTeX2e, 8 eps figures, contribution to proceedings of International Conference on Quantum Field Theory, High-Energy Physics, and Cosmology (July 18-21, 2022; JINR, Dubna, Russia), to be published in Phys. Part. Nucl. Lett

A Data Science Approach to Study the Water Storage Capacity in Rocky Planet Mantles: Earth, Mars, and Exoplanets [CL]

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http://arxiv.org/abs/2304.03700


Nominally anhydrous minerals (NAMs) are the primary carriers of water in rocky planet mantles. Therefore, studying water solubilities of major NAMs in the mantle can help us estimate the water storage capacities of rocky planet mantles and indirectly constrain the actual water contents of their interiors. By using data science methods such as statistics and statistical learning algorithms, in this paper, current modeling studies on the mantle water storage capacities of Earth, Mars, and exoplanets have been introduced and summarized. Firstly, the thermodynamic model for mantle water storage capacity has been reviewed. Then, based on the two case studies on Earth and Mars, how to translate atomic-scale experimental data of water solubility and their measurement errors into planetary-scale models of mantle water storage capacity has been explored by using robust regression, Monte Carlo methods, and bootstrap aggregation algorithms. Thirdly, how the large sample data from the exoplanet observational campaigns can help us understand the statistical properties of the mantle water storage capacities of rocky exoplanets has been introduced. Finally, the application limitations of data science methods in mineral physics research have been discussed, and how to better combine statistics and statistical algorithms with mineral physics data research has been prospected.

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J. Dong
Mon, 10 Apr 23
35/36

Comments: 14 pages, 7 figures, a review article accepted by Bulletin of Mineralogy, Petrology and Geochemistry, in Chinese

Searching for Primordial Black Holes with the Einstein Telescope: impact of design and systematics [CL]

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http://arxiv.org/abs/2304.03160


Primordial Black Holes (PBHs) have recently attracted much attention as they may explain some of the LIGO/Virgo/KAGRA observations and significantly contribute to the dark matter in our universe. The next generation of Gravitational Wave (GW) detectors will have the unique opportunity to set stringent bounds on this putative population of objects. Focusing on the Einstein Telescope (ET), in this paper we analyse in detail the impact of systematics and different detector designs on our future capability of observing key quantities that would allow us to discover and/or constrain a population of PBH mergers. We also perform a population analysis, with a mass and redshift distribution compatible with the current observational bounds. Our results indicate that ET alone can reach an exquisite level of accuracy on the key observables considered, as well as detect up to tens of thousands of PBH binaries per year, but for some key signatures (in particular high–redshift sources) the cryogenic instrument optimised for low frequencies turns out to be crucial, both for the number of observations and the error on the parameters reconstruction. As far as the detector geometry is concerned, we find that a network consisting of two separated L–shaped interferometers of 15 (20)~km arm length, oriented at $45^{\circ}$ with respect to each other performs better than a single triangular shaped instrument of 10 (15)~km arm length, for all the metrics considered.

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G. Franciolini, F. Iacovelli, M. Mancarella, et. al.
Fri, 7 Apr 23
2/50

Comments: 24 pages, 13 figures

Local Limit of Nonlocal Gravity: A Teleparallel Extension of General Relativity [CL]

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http://arxiv.org/abs/2212.05536


We describe a general constitutive framework for a teleparallel extension of the general theory of relativity. This approach goes beyond the teleparallel equivalent of general relativity (TEGR) by broadening the analogy with the electrodynamics of media. In particular, the main purpose of this paper is to investigate in detail a local constitutive extension of TEGR that is the local limit of nonlocal gravity (NLG). Within this framework, we study the modified FLRW cosmological models. Of these, the most cogent turns out to be the modified flat model which is shown to be inconsistent with the existence of a positive cosmological constant. Moreover, dynamic dark energy and other components of the modified flat model evolve differently with the expansion of the universe as compared to the standard flat cosmological model. The observational consequences of the modified flat model are briefly explored and it is shown that the model is capable of resolving the H_0 tension.

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J. Tabatabaei, S. Baghram and B. Mashhoon
Fri, 7 Apr 23
7/50

Comments: 30 pages; v2: expanded discussion of the modified flat model regarding H_0 tension

Azimuthal fluctuations and number of muons at the ground in muon-depleted proton air showers at PeV energies [CL]

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http://arxiv.org/abs/2304.02988


Muon counting is an effective strategy for discriminating between gamma and hadron-initiated air showers. However, their detection, which requires shielded detectors, is highly costly and almost impossible to implement in large ${\rm km^2}$ environmentally sensitive areas. This work shows that the gamma/hadron discriminators, based on the new $LCm$ variable and the number of muons, have equivalent proton rejection levels at the PeV energies. It is, therefore, possible to build, at an affordable cost, a large, high-performant, wide field-of-view gamma-ray observatory.

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A. Bakalová, R. Conceição, L. Gibilisco, et. al.
Fri, 7 Apr 23
10/50

Comments: N/A

Non-thermal Dark Matter via Lepton Portal: Hubble Tension and Stellar Cooling [CL]

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http://arxiv.org/abs/2304.02904


We propose a new non-thermal dark matter which feebly couples to the standard model charged leptons.The feeble interactions allow it $(1)$ to freeze-in from standard model thermal bath with its relic density being a partial or a whole of the observed dark matter density and $(2)$ to radiatively decay to two photons in the dark matter mass ranges of order keV scale with lifetime larger than the age of Universe.These features make this non-thermal dark matter a realistic realization of dark matter with late-time decay as a solution to Hubble tension.We show that the $68\%$ CL best fit value of $H_{0}=68.3~(69.6)$ km s$^{-1}$Mpc$^{-1}$ compared to CMB+BAO (+LSS) data sets.We then use complimentary stellar cooling data to place stringent constraints on the parameter space.While the universal coupling scenario is excluded, the hierarchical coupling scenario can be tested by future observations on white dwarfs after a careful look into photon annihilation, Primakoff and Bremsstrahlung emission of the dark matter in various stellar systems.The viable parameter space may be linked to anomalies in future X-ray telescopes.

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Z. Xu, R. Zhang and S. Zheng
Fri, 7 Apr 23
13/50

Comments: 19 pages, 7 figures

On the detectability of higher harmonics with LISA [CL]

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http://arxiv.org/abs/2304.03142


Supermassive black hole binaries (SMBHB) are expected to be detected by the future space-based gravitational-wave detector LISA with a large signal-to-noise ratio (SNR). This prospect enhances the possibility of differentiating higher harmonics in the inspiral-merger-ringdown (IMR) waveform. In this study, we test the ability of LISA to identify the presence of different modes in the IMR waveform from a SMBHB. We analyze the contribution of each mode to the total SNR for different sources. We show that higher modes, in particular, the mode $(3, 3)$ and $(4, 4)$, can dominate the signal observed through the LISA detector for SMBHB of the order of $10^8 M_\odot$. With Bayesian analysis, we can discriminate models with different IMR modes. While higher modes are often considered to be orthogonal, it is no longer the case in the merger-ringdown phase. Therefore, omitting harmonics not only diminishes the SNR but can also lead to biases in the parameter estimation. We analyze the bias for each model for our example system and quantify the threshold SNR where we can expect the parameter bias to be comparable to the statistical error. Our work highlights the importance of higher modes to describe the gravitational waveform of events detected by LISA.

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C. Pitte, Q. Baghi, S. Marsat, et. al.
Fri, 7 Apr 23
16/50

Comments: 20 pages, 12 figures, submitted to PRD

Right-Handed Neutrino Dark Matter with Forbidden Annihilation [CL]

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http://arxiv.org/abs/2304.02997


The seesaw mechanism with three right-handed neutrinos has one as a well-motivated dark matter candidate if stable and the other two can explain baryon asymmetry via the thermal leptogenesis scenario. We explore the possibility of introducing additional particles to make the right-handed neutrino dark matter in thermal equilibrium and freeze out through a forbidden annihilation channel. Nowadays in the Universe, this forbidden channel can be reactivated by a strong gravitational potential such as the supermassive black hole in our galaxy center. The Fermi-LAT gamma ray data and dark matter relic density require this right-handed neutrino dark matter to have mass below $100\,$GeV and the existence of an additional boson $\phi$ that can be tested at future lepton colliders.

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Y. Cheng, S. Ge, J. Sheng, et. al.
Fri, 7 Apr 23
17/50

Comments: 7 pages, 1 figures

$\mathbf {SU(\infty)}$-QGR Quantumania: Everything, Everywhere, All At Once [CL]

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http://arxiv.org/abs/2304.02761


$SU(\infty)$-QGR is a quantum approach to Universe and gravity. Its main assumption is infinite mutually commuting observables in the Universe, leading to representation of $SU(\infty)$ by its Hilbert spaces and those of its subsystems. The Universe as a whole is static, topological, and characterized by two continuous parameters. Nonetheless, quantum fluctuations induce clustering and finite rank internal symmetries, which approximately divide the Universe to infinite interacting subsystems. Their Hilbert space depends on an additional dimensionful parameter, and selection of a subsystem as clock induces a relative dynamics, with $SU(\infty)$ sector as gravity. The Lagrangian defined on the (3+1)-dimensional parameter space is Yang-Mills for both symmetries. When quantumness of gravity is undetectable, it is perceived as curvature of an effective spacetime.

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H. Ziaeepour
Fri, 7 Apr 23
21/50

Comments: 12 pages, no figure. Essay submitted to 2023 Awards for Essays on Gravitation

The indication for $^{40}$K geo-antineutrino flux with Borexino phase-III data [CL]

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http://arxiv.org/abs/2304.02747


We provide the indication of high flux of $^{40}$K geo-antineutrino and geo-neutrino ($^{40}$K-geo-($\bar{\nu} + \nu$)) with Borexino Phase III data. This result was obtained by introducing a new source of single events, namely $^{40}$K-geo-($\bar{\nu} + \nu$) scattering on electrons, in multivariate fit analysis of Borexino Phase III data. Simultaneously we obtained the count rates of events from $^7$Be, $pep$ and CNO solar neutrinos. These count rates are consistent with the prediction of the Low metallicity Sun model SSM B16-AGSS09. MC pseudo-experiments showed that the case of High metallicity Sun and absence of $^{40}$K-geo-($\bar{\nu} + \nu$) can not imitate the result of multivariate fit analysis of Borexino Phase III data with introducing $^{40}$K-geo-($\bar{\nu} + \nu$) events. We also provide arguments for the high abundance of potassium in the Earth.

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L. Bezrukov, I. Karpikov and V. Sinev
Fri, 7 Apr 23
22/50

Comments: 17 pages, 7 figures. arXiv admin note: substantial text overlap with arXiv:2202.08531

Asymptotic normalization coefficients of alpha-particle removal from $^{16}$O($3^-,2^+,1^-$) [CL]

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http://arxiv.org/abs/2304.02821


Asymptotic normalization coefficients (ANC) determine the overall normalization of cross sections of peripheral radiative capture reactions. In a recent paper [Blokhintsev {\em et al.}, Eur. Phys. J. A {\bf 58}, 257 (2022)], we considered the ANC $C_0$ for the virtual decay $^{16}$O$(0^+; 6.05$ MeV)$\to \alpha+^{12}$C(g.s.). In the present paper, which can be regarded as a continuation of the previous, we treat the ANCs $C_l$ for the vertices $^{16}$O$(J^\pi)\to \alpha+^{12}$C(g.s.) corresponding to the other three bound excited states of $^{16}$O ($J^\pi=3^-$, $2^+$, $1^-$, $l=J$). ANCs $C_l$ ($l=3,\,2,\,1$) are found by analytic continuation in energy of the $\alpha^{12}$C $l$-wave partial scattering amplitudes, known from the phase-shift analysis of experimental data, to the pole corresponding to the $^{16}$O bound state and lying in the unphysical region of negative energies. To determine $C_l$, the scattering data are approximated by the sum of polynomials in energy in the physical region and then extrapolated to the pole. For a more reliable determination of the ANCs, various forms of functions expressed in terms of phase shifts were used in analytical approximation and subsequent extrapolation.

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L. Blokhintsev, A. Kadyrov, A. Mukhamedzhanov, et. al.
Fri, 7 Apr 23
30/50

Comments: arXiv admin note: substantial text overlap with arXiv:2208.09587

Axial perturbations of black holes in scalar-tensor gravity: near-horizon behaviour [CL]

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http://arxiv.org/abs/2304.03055


We consider axial (or odd-parity) perturbations of non-spinning hairy black holes (BH) in shift-symmetric DHOST (Degenerate Higher-Order Scalar-Tensor) theories, including terms quartic and cubic in second derivatives of the scalar field. We give a new formulation of the effective metric in which axial perturbations propagate as in general relativity. We then introduce a generic parametrization of the effective metric in the vicinity of the background BH horizon. Writing the dynamics of the perturbations in terms of a Schr\”odinger-like operator, we discuss in which cases the operator is (essentially) self-adjoint, thus leading to an unambiguous time evolution, according to the choice of parameters characterizing the near-horizon effective metric. This is in particular useful to investigate the stability of the perturbations. We finally illustrate our general analysis with two examples of BH solutions.

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K. Noui, H. Roussille and D. Langlois
Fri, 7 Apr 23
34/50

Comments: 24 pages, 3 appendices

Pitch-angle diffusion through localized interactions with sharp magnetic field bends in MHD turbulence [CL]

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http://arxiv.org/abs/2304.03023


When a particle crosses a region of space where the curvature radius of the magnetic field line shrinks below the gyroradius $r_{\rm g}$, it experiences a non-adiabatic (magnetic moment violating) change in pitch-angle. The present paper carries that observation into MHD turbulence to examine the influence of intermittent, sharp bends of the magnetic field lines on particle transport. On the basis of dedicated measurements in a simulation of incompressible turbulence, it is argued that regions of sufficiently large curvature may exist in sufficient numbers on all scales to promote pitch-angle diffusion. The parallel mean free path predicted by the powerlaw statistics of the curvature strength scales as $\sim r_{\rm g}^{0.3}\,\ell_{\rm c}^{0.7}$ ($\ell_{\rm c}$ coherence scale of the turbulence), of direct interest to cosmic-ray phenomenology. Particle tracking in that numerical simulation confirms that the magnetic moment diffuses through localized, violent interactions, in agreement with the above picture. Correspondingly, the overall transport process is non-Brownian up to length scales $\gtrsim\ell_{\rm c}$.

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M. Lemoine
Fri, 7 Apr 23
50/50

Comments: 15 pages, 6 figures

Eternal binaries [CL]

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http://arxiv.org/abs/2304.02039


The two-body problem is extensively studied in open systems and asymptotically flat spacetimes. However, there are many systems where radiation is trapped: they range from radiating charges in cavities to low-energy excitations of massive degrees of freedom, to anti-de Sitter spacetimes. Here, we study the problem of motion of a pointlike particle orbiting a massive compact object inside a cavity. We first show that – assuming circular motion – there are initial conditions for which the self-force vanishes and the binary is eternal. We then consider the evolution of the system under radiation reaction in a toy model which we argue captures the essentials of orbiting particles. We show that eternal circular binaries may exist. We also show that the presence of cavity modes leads to chaos in regimes of strong coupling or when the system is initialized close enough to a resonance. Our results have implications for physics in anti-de Sitter spacetimes and possibly for binaries evolving within dark matter haloes, if it consists on massive fundamental fields.

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J. Redondo-Yuste, V. Cardoso, C. Macedo, et. al.
Thu, 6 Apr 23
2/76

Comments: 21 pages, 17 figures

The Next Generation Event Horizon Telescope Collaboration: History, Philosophy, and Culture [CL]

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http://arxiv.org/abs/2304.02463


This white paper outlines the plans of the History Philosophy Culture Working Group of the Next Generation Event Horizon Telescope Collaboration.

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P. Galison, J. Doboszewski, J. Elder, et. al.
Thu, 6 Apr 23
3/76

Comments: 23 pages, 1 figure

The Lense-Thirring effect on the Galilean moons of Jupiter [CL]

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http://arxiv.org/abs/2304.02289


The perspectives of detecting the general relativistic Lense-Thirring effect on the orbits of the Galilean moons of Jupiter induced by its angular momentum ${\boldsymbol{S}}$ are preliminarily investigated. Numerical integrations over one century show that the expected gravitomagnetic signatures of some observables such as the satellites’ right ascension $\alpha$ and declination $\delta$ are as large as tens of arcseconds for Io, while for Callisto they drop to the $\simeq 0.2\,\mathrm{arcseconds}$ level; the shifts in the transverse component $T$ of the orbit range from 40 km for Io to 2 km for Callisto. Major competing effects due to the mismodeling in the zonal multipoles $J_\ell,\,\ell=2,\,3,\,4,\,\ldots$ of the Jovian non-spherically symmetric gravity field and in the Jupiter’s spin axis ${\boldsymbol{\hat{k}}}$ should have a limited impact, especially in view of the future improvements in determing such parameters expected after the completion of the ongoing Juno mission in the next few years. Present-day accuracy in knowing the orbits of Io, Europa, Ganymede and Callisto is of the order of 10 milliarcseconds, to be likely further improved by the approved JUICE and Clipper missions. This suggests that the Lense-Thirring effect in the main Jovian system of moons might be detectable with dedicated data reductions in which the gravitomagnetic field is explicitly modeled and solved-for.

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L. Iorio
Thu, 6 Apr 23
8/76

Comments: LaTex2e, 24 pages, 12 figures, no tables

Gravitational waves from cosmic strings associated with pseudo-Nambu-Goldstone dark matter [CL]

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http://arxiv.org/abs/2304.02506


We study stochastic gravitational waves from cosmic strings generated in an ultraviolet-complete model for pseudo-Nambu-Goldstone dark matter with a hidden $\mathrm{U(1)}$ gauge symmetry. The dark matter candidate in this model can naturally evade direct detection bounds and easily satisfy other phenomenological constraints. The bound on the dark matter lifetime implies an ultraviolet scale higher than $10^9~\mathrm{GeV}$. The spontaneous $\mathrm{U(1)}$ symmetry breaking at such a high scale would induce cosmic strings with high tension, resulting in a stochastic gravitational wave background with a high energy density. We investigate the constraints from current gravitational wave experiments as well as the future sensitivity. We find that most of the viable parameter points could be well studied in future gravitational wave experiments.

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Z. Qiu and Z. Yu
Thu, 6 Apr 23
16/76

Comments: 23 pages, 6 figures

Gravitoelectric dynamical tides at second post-Newtonian order [CL]

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http://arxiv.org/abs/2304.02030


We present a gravitoelectric quadrupolar dynamical tidal-interaction Hamiltonian for a compact binary system, that is valid to second order in the post-Newtonian expansion. Our derivation uses the diagrammatic effective field theory approach, and involves Feynman integrals up to two loops, evaluated with the dimensional regularization scheme. We also derive the effective Hamiltonian for adiabatic tides, obtained by taking the appropriate limit of the dynamical effective Hamiltonian, and we check its validity by verifying the complete Poincar\’e algebra. In the adiabatic limit, we also calculate two gauge-invariant observables, namely, the binding energy for a circular orbit and the scattering angle in a hyperbolic scattering. Our results are important for developing accurate gravitational waveform models for neutron-star binaries for present and future gravitational-wave observatories.

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M. Mandal, P. Mastrolia, H. Silva, et. al.
Thu, 6 Apr 23
23/76

Comments: 20 pages, 2 figures, 1 table