Tag Archives: Strongly Correlated Electrons

Strong-Field Physics in QED and QCD: From Fundamentals to Applications [CL]

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http://arxiv.org/abs/2305.03865


We provide a pedagogical review article on fundamentals and applications of the quantum dynamics in strong electromagnetic fields in QED and QCD. The fundamentals include the basic picture of the Landau quantization and the resummation techniques applied to the class of higher-order diagrams that are enhanced by large magnitudes of the external fields. We then discuss observable effects of the vacuum fluctuations in the presence of the strong fields, which consist of the interdisciplinary research field of nonlinear QED. We also discuss extensions of the Heisenberg-Euler effective theory to finite temperature/density and to non-Abelian theories with some applications. Next, we proceed to the paradigm of the dimensional reduction emerging in the low-energy dynamics in the strong magnetic fields. The mechanisms of superconductivity, the magnetic catalysis of the chiral symmetry breaking, and the Kondo effect are addressed from a unified point of view in terms of the renormalization-group method. We provide an up-to-date summary of the lattice QCD simulations in magnetic fields for the chiral symmetry breaking and the related topics as of the end of 2022. Finally, we discuss novel transport phenomena induced by chiral anomaly and the axial-charge dynamics. Those discussions are supported by a number of appendices.

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K. Hattori, K. Itakura and S. Ozaki
Tue, 9 May 23
53/88

Comments: Prepared for an invited review article

Electrical and Thermal Conductivity of High-Pressure Solid Iron [CL]

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http://arxiv.org/abs/2210.10132


We study the electrical and thermal conductivity of iron at high pressures using time-dependent density functional theory. In doing so, we particularly consider the impact of a Hubbard correction (+\textit{U}) specifically for regions where strong electron correlations are present. Using the TDDFT+U methodology, we examine the anisotropy in the thermal conductivity of HCP iron, which may provide insights into the transport properties at conditions relevant to the core-mantle boundary and the interior of the Earth.

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K. Ramakrishna, M. Lokamani, A. Baczewski, et. al.
Thu, 20 Oct 22
41/74

Comments: N/A

Turbulence in Two-Dimensional Relativistic Hydrodynamic Systems with a Lattice Boltzmann Model [CL]

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http://arxiv.org/abs/2205.04658


Using a Lattice Boltzmann hydrodynamic computational modeler to simulate relativistic fluid systems we explore turbulence in two-dimensional relativistic flows. We first a give a pedagogical description of the phenomenon of turbulence and its characteristics in a two-dimensional system. The classical Lattice Boltzmann Method and its extension to relativistic fluid systems is then described. The model is tested against a system incorporating a random stirring force in k-space and then applied to a realistic sample of graphene.
Part I: We investigate the relativistic adaptation of the Lattice Boltzmann Method reproducing a turbulent, two-dimensional, massless hydrodynamic system with a zero-averaged stirring force randomly generated in momentum space. The numeric formulation is evaluated and the flow characteristics produced are compared to properties of classical turbulence. The model can reasonably be expected to offer quantitative simulations of charged fluid flows in two-dimensional relativistic fluid systems.
Part II: At low Reynolds numbers, the wind flow in the wake of a single wind turbine is generally not turbulent. However, turbines in wind farms affect each other’s wakes so that a turbulent flow can arise. An analogue of this effect for the massless charge carrier flow around obstacles in graphene is outlined. We use a relativistic hydrodynamic simulation to analyze the flow in a sample containing impurities. Depending on the density of impurities in the sample, we indeed find evidence for a potentially turbulent flow and discuss experimental consequences.

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M. Watson
Wed, 11 May 22
31/60

Comments: 90 pages, 23 figures. arXiv admin note: substantial text overlap with arXiv:2101.06187, arXiv:2202.07839

Relativistic Wind Farm Effect: Possibly Turbulent Flow of a Charged, Massless Relativistic Fluid in Graphene [CL]

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http://arxiv.org/abs/2202.07839


At low Reynolds numbers, the wind flow in the wake of a single wind turbine is generally not turbulent. However, turbines in wind farms affect each other’s wakes so that a turbulent flow can arise. In the present work, an analogue of this effect for the massless charge carrier flow around obstacles in graphene is outlined. We use a relativistic hydrodynamic simulation to analyze the flow in a sample containing impurities. Depending on the density of impurities in the sample, we indeed find evidence for potentially turbulent flow and discuss experimental consequences.

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M. Watson
Thu, 17 Feb 22
40/60

Comments: 7 pages, 9 figures

Ferromagnetic instability in PAAI in the sky [CL]

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http://arxiv.org/abs/2105.09528


We study an idealised plasma of fermions, coupled through an abelian gauge force $U(1)_X$, and which is asymmetric in that the masses of the oppositely charged species are greatly unequal. The system is dubbed PAAI, plasma asym\’etrique, ab\’elien et id\’ealis\’e. It is argued that due to the ferromagnetic instability that arises, the ground state gives rise to a complex of domain walls. This complex being held together by stresses much stronger than cosmic gravity, does not evolve with the scale factor and along with the heavier oppositely charged partners simulates the required features of Dark Energy with mass scale for the lighter fermions in the micro-eV to nano-eV range. Further, residual $X$-magnetic fields through mixture with standard magnetic fields, can provide the seed for cosmic-scale magnetic fields. Thus the scenario can explain several cosmological puzzles including Dark Energy.

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R. MacKenzie, M. Paranjape and U. Yajnik
Fri, 21 May 21
63/66

Comments: 9 pages, 1 figure, Talk at the 11th International Symposium “Quantum Theory and Symmetries” (July 1st to 5th, 2019, CRM, Univ. of Montreal). arXiv admin note: substantial text overlap with arXiv:2010.10034, arXiv:1901.00995

Quantum analysis of second-order effects in superconducting travelling-wave parametric amplifiers [IMA]

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http://arxiv.org/abs/2104.06350


We have performed a quantum mechanical analysis of travelling-wave parametric amplifiers (TWPAs) in order to investigate five experimental phenomena related to their operations, namely the effect of impedance mismatch, the presence of upper idler modes, the presence of quantum and thermal noise, the generation of squeezed states, and the preservation of pre-squeezed states during amplification. Our analysis uses momentum operators to describe the spatial evolution of quantised modes along a TWPA. We calculate the restriction placed on pump amplitude as well as amplifier gain as a result of impedance mismatch between a TWPA and its external system. We apply our analysis to upper idler modes and demonstrate that they will result in suppressed gain. We show that an ideal TWPA is indeed quantum-limited – i.e. it introduces a half-quantum of zero-point fluctuation which is the minimum possible noise contribution for a phase-preserving linear amplifier. We analyse the thermal noise associated with a TWPA by considering the effect of distributed sources along an amplifier transmission line. Our analysis predicts a doubling of thermal noise in the high gain limit as a result of wave-mixing between signal and idler modes. We study the operation of a TWPA in the presence of a DC bias current, and have shown that highly squeezed states can in principle be generated. However, amplifying a pre-squeezed state using a non-degenerate TWPA generally reduces the squeezing advantage.

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S. Zhao and S. Withington
Wed, 14 Apr 2021
65/67

Comments: N/A

Two Dimensional Turbulence in a Massless Fluid with a Relativistic Lattice Boltzmann Model [CL]

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http://arxiv.org/abs/2101.06187


We investigate a relativistic adaptation of the Lattice Boltzmann Method that reproduces the equations of motion for a turbulent, two-dimensional, massless hydrodynamic system. The classical Lattice Boltzmann Method and its extension to relativistic fluid dynamics is described. The numeric formulation is evaluated using a zero-averaged stirring force introduced into the numerics to induce turbulence, and the flow characteristics produced are compared to properties of a classical turbulent hydrodynamic flow. The model can reasonably be expected to offer quantitative simulations of electron fluid flows in graphene or Kagome lattices.

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M. Watson
Mon, 18 Jan 21
7/41

Comments: 28 pages, 11 Figures, Comments Welcome

2-group global symmetries, hydrodynamics and holography [CL]

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http://arxiv.org/abs/2010.00320


2-group global symmetries are a particular example of how higher-form and conventional global symmetries can fuse together into a larger structure. We construct a theory of hydrodynamics describing the finite-temperature realization of a 2-group global symmetry composed out of $U(1)$ zero-form and $U(1)$ one-form symmetries. We study aspects of the thermodynamics from a Euclidean partition function and derive constitutive relations for ideal hydrodynamics from various points of view. Novel features of the resulting theory include an analogue of the chiral magnetic effect and a chiral sound mode propagating along magnetic field lines. We also discuss a minimalist holographic description of a theory dual to 2-group global symmetry and verify predictions from hydrodynamic descriptions. Along the way we clarify some aspects of symmetry breaking in higher-form theories at finite temperature.

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N. Iqbal and N. Poovuttikul
Fri, 2 Oct 20
61/65

Comments: 32 pages + appendices, 6 figures

Mixed State Dynamics with Non-Local Interactions [CEA]

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http://arxiv.org/abs/2002.09173


The evolution of degenerate matter out of equilibrium is a topic of interest in fields such as condensed matter, nuclear and atomic physics, and increasingly cosmology, including inflaton physics prior to reheating. This follow-up paper extends the recent paper on the super-de Broglie dynamics of pure condensates of non-relativistic identical particles subject to non-local two-body interactions to the dynamics of mixed states. It is found that the two-body correlation function plays an increasingly dynamical role in these systems, driving the development of condensates and distributed phases alike. Examples of distribution and correlation evolution are presented, including instances of collapse, bound and unbound states, and phonons in the bulk. Potential applications are also discussed.

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E. Lentz, L. Lettermann, T. Quinn, et. al.
Mon, 24 Feb 20
7/49

Comments: 6 pages, 3 figures

Real-Time Corrections to the Effective Potential [CL]

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http://arxiv.org/abs/1905.00219


Non-perturbatively generated effective potentials play an extremely useful and often critical role in string and inflationary model building. These potentials are typically computed by methods that assume the system is in equilibrium. For systems out of equilibrium, like an inflaton rolling down its potential, there are corrections to the semi-classical evolution due to transient phenomena. We provide a new qualitative and quantitative understanding of non-perturbative effects in real time for a wide class of toy quantum mechanical models. We derive an effective Schr\”{o}dinger equation that does not rely on any notion of equilibrium and captures the low-energy dynamics supposedly described by the effective potential. We find that there are potentially large corrections to this potential that are not captured by standard equilibrium techniques, and quantify when these corrections significantly alter the effective dynamics.

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G. Pimentel and J. Stout
Thu, 2 May 19
18/45

Comments: 1+36 pages, 12 figures, 4 appendices

Imaging black holes through AdS/CFT [CL]

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http://arxiv.org/abs/1811.12617


Clarifying conditions for the existence of a gravitational picture for a given quantum field theory (QFT) is one of the fundamental problems in the AdS/CFT correspondence. We propose a direct way to demonstrate the existence of the dual black holes: Imaging an Einstein ring. We consider a response function of the thermal QFT on a two-dimensional sphere under a time-periodic localized source. The dual gravity picture, if exists, is a black hole in an asymptotic global AdS$_4$ and a bulk probe field with a localized source on the AdS boundary. The response function corresponds to the asymptotic data of the bulk field propagating in the black hole spacetime. We find a formula which converts the response function to the image of the dual black hole: The view of the sky of the AdS bulk from a point on the boundary. Using the formula, we demonstrate that, for a thermal state dual to the Schwarzschild-AdS$_4$ spacetime, the Einstein ring is constructed from the response function. The evaluated Einstein radius is found to be determined by the total energy of the dual QFT.

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K. Hashimoto, K. Murata and S. Kinoshita
Mon, 3 Dec 18
38/63

Comments: 22 pages, 12 figures

One-form superfluids and magnetohydrodynamics [CL]

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http://arxiv.org/abs/1811.04913


We use the framework of generalised global symmetries to study various hydrodynamic regimes of hot electromagnetism. We formulate the hydrodynamic theories with an unbroken or a spontaneously broken U(1) one-form symmetry. The latter of these describes a one-form superfluid, which is characterised by a vector Goldstone mode and a two-form superfluid velocity. Two special limits of this theory have been studied in detail: the string fluid limit where the U(1) one-form symmetry is partly restored, and the electric limit in which the symmetry is completely broken. The transport properties of these theories are investigated in depth by studying the constraints arising from the second law of thermodynamics and Onsager’s relations at first order in derivatives. We also write down a hydrostatic effective action for the Goldstone modes in these theories and use it to characterise the space of all equilibrium configurations. To make explicit contact with hot electromagnetism, the traditional treatment of magnetohydrodynamics, where the electromagnetic photon is incorporated as a dynamical degrees of freedom, is extended to include parity-violating contributions. We argue that the chemical potential and electric fields are not independently dynamical in magnetohydrodynamics, and illustrate how to eliminate these within the hydrodynamic derivative expansion using Maxwell’s equations. Additionally, a new hydrodynamic theory of non-conducting, but polarised, plasmas is formulated, focusing primarily on the magnetically dominated sector. Finally, it is shown that the different limits of one-form superfluids formulated in terms of generalised global symmetries are exactly equivalent to magnetohydrodynamics and the hydrodynamics of non-conducting plasmas at the non-linear level.

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J. Armas and A. Jain
Tue, 13 Nov 18
5/74

Comments: v1: 60 + 1 pages, 1 figure, 4 tables

Effective field theory of magnetohydrodynamics from generalized global symmetries [CL]

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http://arxiv.org/abs/1811.04879


We introduce an effective action for non-dissipative magnetohydrodynamics. A crucial guiding principle is the generalized global symmetry of electrodynamics, which naturally leads to introducing a “dual photon” as the degree of freedom responsible for the electromagnetic component of the fluid. The formalism includes additional degrees of freedom and symmetries which characterize the hydrodynamic regime. By suitably enhancing one of the symmetries, the theory becomes force-free electrodynamics. The symmetries furthermore allow to systematize local and non-local conserved helicities. We also discuss higher-derivative corrections.

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P. Glorioso and D. Son
Tue, 13 Nov 18
18/74

Comments: 13 pages

Astrophysical Quantum Matter: Spinless charged particles on a magnetic dipole sphere [CL]

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http://arxiv.org/abs/1811.03109


We consider the quantum mechanics of a spinless charged particle on a 2-dimensional sphere. When threaded with a magnetic monopole field, this is the well-known Haldane sphere that furnishes a translationally-invariant, incompressible quantum fluid state of a gas of electrons confined to the sphere. This letter presents the results of a novel variant of the Haldane solution where the monopole field is replaced by that of a dipole. We argue that this system is relevant to the physics on the surface of compact astrophysical objects like neutron stars.

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J. Murugan, J. Shock and R. Slayen
Fri, 9 Nov 18
61/64

Comments: 4+1 pages, 3 figures

Condensate Dynamics with Non-Local Interactions [CEA]

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http://arxiv.org/abs/1808.06378


Systems of identical particles possessing non-local interactions are capable of exhibiting extra-classical properties beyond the characteristic quantum length scales. This letter derives the dynamics of such systems in the non-relativistic and degenerate limit, showing the effect of exchange symmetry and correlations on structure both in and out of equilibrium. Such descriptions may be crucial to understanding systems ranging from nuclei to dark matter. Appropriate limits for restoring the mean-field description are also discussed.

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E. Lentz, T. Quinn and L. Rosenberg
Tue, 21 Aug 18
66/71

Comments: 4 pages, 1 figure, submitted to PRD Rapid Communications

Magnetohydrodynamics as superfluidity [CL]

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http://arxiv.org/abs/1808.01939


We show that relativistic magnetohydrodynamics (MHD) is described by a novel theory of superfluidity. This new theory is characterised by a vector Goldstone mode that originates from the spontaneous breaking of a one-form symmetry. The complete formulation of one-form superfluidity admits the existence of several limits, including a string fluid limit. We explicitly show that the equations governing MHD, when taken onshell by solving Maxwell’s equations, are precisely those of a one-form superfluid in the string fluid limit. These results provide a precise and consistent dual formulation of MHD, including of its equilibrium configurations.

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J. Armas and A. Jain
Tue, 7 Aug 18
68/68

Comments: v1: 5 pp

Relativistic Fluid Dynamics Out of Equilibrium — Ten Years of Progress in Theory and Numerical Simulations of Nuclear Collisions [CL]

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http://arxiv.org/abs/1712.05815


Ten years ago, relativistic viscous fluid dynamics was formulated from first principles in an effective field theory framework, based entirely on the knowledge of symmetries and long-lived degrees of freedom. In the same year, numerical simulations for the matter created in relativistic heavy-ion collision experiments became first available, providing constraints on the shear viscosity in QCD. The field has come a long way since then. We present the current status of the theory of non-equilibrium fluid dynamics in 2017, including the divergence of the fluid dynamic gradient expansion, resurgence, non-equilibrium attractor solutions, the inclusion of thermal fluctuations as well as their relation to microscopic theories. Furthermore, we review the theory basis for numerical fluid dynamics simulations of relativistic nuclear collisions, and comparison of modern simulations to experimental data for nucleus-nucleus, nucleus-proton and proton-proton collisions.

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P. Romatschke and U. Romatschke
Mon, 25 Dec 17
20/37

Comments: 196 pages, 35 figures; uninvited review; v1: comments, criticism, citation requests and publisher recommendations welcome

Phase diagram of hydrogen and a hydrogen-helium mixture at planetary conditions by Quantum Monte Carlo simulations [CL]

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http://arxiv.org/abs/1709.08648


Understanding planetary interiors is directly linked to our ability of simulating exotic quantum mechanical systems such as hydrogen (H) and hydrogen-helium (H-He) mixtures at high pressures and temperatures. Equations of State (EOSs) tables based on Density Functional Theory (DFT), are commonly used by planetary scientists, although this method allows only for a qualitative description of the phase diagram, due to an incomplete treatment of electronic interactions. Here we report Quantum Monte Carlo (QMC) molecular dynamics simulations of pure H and H-He mixture. We calculate the first QMC EOS at 6000 K for an H-He mixture of a proto-solar composition, and show the crucial influence of He on the H metallization pressure. Our results can be used to calibrate other EOS calculations and are very timely given the accurate determination of Jupiter’s gravitational field from the NASA Juno mission and the effort to determine its structure.

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G. Mazzola, R. Helled and S. Sorella
Wed, 27 Sep 2017
21/81

Comments: 4 pages + supplementary methods and figures

Pyrite FeO2: material "in between'" oxides and peroxides [CL]

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http://arxiv.org/abs/1705.08085


Recent discovery [Nature 534, 241 (2016)] of FeO$_2$, which can be an important ingredient of the Earth’s lower mantle and which in particular may serve as an extra source of oxygen and water at the Earth’s surface and atmosphere, opens new perspectives for geophysics and geochemistry, but this is also an extremely interesting material from physical point of view. We found that in contrast to naive expectations Fe is nearly 3+ in this material, which strongly affects its magnetic properties and makes it qualitatively different from well known sulfide analogue – FeS$_2$. Doping, which is most likely to occur in the Earth’s mantle, makes FeO$_2$ much more magnetic. In addition we show that unique electronic structure places FeO$_2$ “in between” the usual dioxides and peroxides making this system interesting both for physics and solid state chemistry.

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S. Streltsov, A. Shorikov, S. Skornyakov, et. al.
Wed, 24 May 17
9/70

Comments: N/A

Ab initio and phenomenological studies of the static response of neutron matter [CL]

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http://arxiv.org/abs/1608.03598


We investigate the problem of periodically modulated strongly interacting neutron matter. We carry out ab initio non-perturbative auxiliary-field diffusion Monte Carlo calculations using an external sinusoidal potential in addition to phenomenological two- and three-nucleon interactions. Several choices for the wave function ansatz are explored and special care is taken to extrapolate finite-sized results to the thermodynamic limit. We perform calculations at various densities as well as at different strengths and periodicities of the one-body potential. Our microscopic results are then used to constrain the isovector term from energy-density functional theories of nuclei at many different densities, while making sure to separate isovector contributions from bulk properties. Lastly, we use our results to extract the static density-density linear response function of neutron matter at different densities. Our findings provide insights into inhomogeneous neutron matter and are related to the physics of neutron-star crusts and neutron-rich nuclei.

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M. Buraczynski and A. Gezerlis
Mon, 15 Aug 16
3/43

Comments: 11 pages, 14 figures

Static Response of Neutron Matter [CL]

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http://arxiv.org/abs/1510.06417


We generalize the problem of strongly interacting neutron matter by adding a periodic external modulation. This allows us to study from first principles a neutron system that is extended and inhomogeneous, with connections to the physics of both neutron-star crusts and neutron-rich nuclei. We carry out fully non-perturbative microscopic Quantum Monte Carlo calculations of the energy of neutron matter at different densities, as well as different strengths and periodicities of the external potential. In order to remove systematic errors, we examine finite-size effects and the impact of the wave function ansatz. We also make contact with energy-density functional theories of nuclei and disentangle isovector gradient contributions from bulk properties. Finally, we calculate the static density-density linear response function of neutron matter and compare it with the response of other physical systems.

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M. Buraczynski and A. Gezerlis
Fri, 23 Oct 15
25/63

Comments: 5 pages, 3 figures

Majorana and the theoretical problem of photon-electron scattering [CL]

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http://arxiv.org/abs/1501.06838


Relevant contributions by Majorana regarding Compton scattering off free or bound electrons are considered in detail, where a (full quantum) generalization of the Kramers-Heisenberg dispersion formula is derived. The role of intermediate electronic states is appropriately pointed out in recovering the standard Klein-Nishina formula (for free electron scattering) by making recourse to a limpid physical scheme alternative to the (then unknown) Feynman diagram approach. For bound electron scattering, a quantitative description of the broadening of the Compton line was obtained for the first time by introducing a finite mean life for the excited state of the electron system. Finally, a generalization aimed to describe Compton scattering assisted by a non-vanishing applied magnetic field is as well considered, revealing its relevance for present day research.

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M. Mauro, S. Esposito and A. Naddeo
Wed, 28 Jan 15
46/58

Comments: latex, amsart, 10 pages, 1 figure

Approaching Pomeranchuk Instabilities from Ordered Phase: A Crossing-symmetric Equation Method [CL]

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http://arxiv.org/abs/1404.5655


We explore features of a 3D Fermi liquid near generalized Pomeranchuk instabilities using a tractable crossing symmetric equation method. We approach the instabilities from the ordered ferromagnetic phase. We find quantum multi-criticality as approach to the ferromagnetic instability drives instability in other channel(s). It is found that a charge nematic instability precedes and is driven by Pomeranchuk instabilities in both the l = 0 spin and density channels.

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K. Reidy, K. Quader and K. Bedell
Thu, 24 Apr 14
4/64