http://arxiv.org/abs/1705.04861
Primordial Black Holes (PBH) arise naturally from high peaks in the curvature power spectrum of near-inflection-point single-field inflation, and could constitute today the dominant component of the dark matter in the universe. In this letter we explore the possibility that a broad spectrum of PBH is formed in models of Critical Higgs Inflation (CHI), where the quasi-inflection point is related to the near-critical value of the RGE running of both the Higgs self-coupling $\lambda(\mu)$ and its non-minimal coupling to gravity $\xi(\mu)$. We show that the peak in the matter spectrum arises at sufficiently small scales that it passes all the observational constraints from the cosmic microwave background (CMB) and large scale structure (LSS) observations. The CMB spectrum at large scales is in agreement with Planck-2015 data, $A_s^2 = 2.1\times10^{-9},\,n_s = 0.957,\,r=0.028,\,dn_s/d\ln k = -0.00144$. The relatively large tensor-to-scalar ratio may be detected soon with B-mode polarization experiments. Moreover, the model predicts a lognormal PBH broad-mass distribution peaked at $\mu_{{\rm PBH}}=4\times10^{-11}\,M\odot$, with dispersion $\sigma_{{\rm PBH}}=1.4$, which is consistent with the present constraints on PBH and may eventually be discovered with microlensing experiments. The stochastic background of gravitational waves coming from the unresolved black-hole-binary (BHB) mergings could also be detected by LISA or PTA. Furthermore, the parameters of the CHI model correspond to a Standard Model Higgs self-coupling running, given by $\lambda_0 = 1.2\times10^{-6}$ and $b\lambda = 0.9\times10^{-5}$ near the critical point, and a running non-minimal coupling, with $\xi_0 = 21$ and $b_\xi = 40.6$, while the critical Higgs value is $\kappa^2\mu^2 = 0.0226$. These values are consistent, within $2\sigma$, with the measured Higgs parameters at the LHC.
J. Ezquiaga, J. Garcia-Bellido and E. Morales
Tue, 16 May 17
19/78
Comments: 4 pages, 4 figures, submitted to PRL
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