Abstract
Extending the standard model with three right-handed neutrinos and a simple QCD axion sector can account for neutrino oscillations, dark matter and baryon asymmetry; at the same time, it solves the strong CP problem, stabilizes the electroweak vacuum and can implement critical Higgs inflation (satisfying all current observational bounds). We perform here a general analysis of dark matter (DM) in such a model, which we call the aνMSM. Although critical Higgs inflation features a (quasi) inflection point of the inflaton potential, we show that DM cannot receive a contribution from primordial black holes in the aνMSM. This leads to a multicomponent axion–sterile neutrino DM and allows us to relate the axion parameters, such as the axion decay constant, to the neutrino parameters. We include several DM production mechanisms: the axion production via misalignment and decay of topological defects as well as the sterile neutrino production through the resonant and non-resonant mechanisms and in the recently proposed CPT-symmetric universe.
Highlights
Despite the remarkable success of the standard model (SM), there is no question that it needs to be extended
In Ref. [13], it was found that Higgs inflation can be realized in its critical version [14,15,16] within the aνMSM: critical Higgs inflation (CHI) occurs when the SM lies extremely close to the border between the absolute stability and metastability of the EW
L, i.e., f (Ωs, θ, ms, L) = 0, and the allowed region in the (θ, ms ) plane is promoted to a band, which is limited by the DW line f (Ωs, θ, ms, 0) = 0. There exists another bound on this band, f (Ωs, θ, ms, Lmax ) = 0, where Lmax is the maximal value of L allowed by observations: the values L > Lmax are ruled out because they would excessively change the abundances of light elements produced during Big Bang nucleosynthesis (BBN) [96]
Summary
Despite the remarkable success of the standard model (SM), there is no question that it needs to be extended. Since in all the sterile neutrino production mechanisms the masses of these neutral fermions are below the ∼1014 GeV scale, they necessarily have a negligible impact on the running and, the parameter space of the aνMSM with absolute EW vacuum stability is enlarged [1]. This is because, generically, a Yukawa coupling (that is proportional to the mass of a fermion) contributes negatively to the β-function of the Higgs quartic coupling, as explained at the end of Section 5.
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