Axion-Sterile-Neutrino Dark Matter

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.

Hearing Higgs with Gravitational Wave Detectors

“…This is the case, for example, setting the experimental inputs as in Sec. 6.1 and the values of the other parameters as follows: M 1 = 10 11 GeV, M 2 = 6.4 × 10 13 GeV, 6 A simple formula for T a dec was proposed by [70] T a dec 9.6 × 10 6 GeV f a 10 10 GeV We observe that this formula gives a T a dec always below f a as long as f a 10 12 GeV, which is required in order not to overproduce dark matter [22]. M 3 > MPl , f a 5 × 10 10 GeV, λ HA (M A ) 0.016, λ A (M A ) 0.10, y(M A ) = 0.1, ξ H (M A ) 14 and ξ A (M A ) −2.6.…”

“…5, while Sec. 6 is devoted to the corresponding analysis in a well-motivated phenomenological completion of the SM below the Planck scale [16,21,22]. The conclusions are given in Sec.…”

“…Such bound has a mild logarithmic dependence on λ A (for e.g. λ A around the scale 10 −1 , it is about 5 × 10 10 GeV [22]). When f a saturates this bound the axion accounts for the whole dark matter [64,65], while for smaller values the rest of dark matter can be explained with the lightest sterile neutrino [66][67][68][69], forming a two-component DM [22].…”

“…Finally, as far as the determination of the dependence λ H and ξ H on φ is concerned, we solve here the RGEs given in the appendix of [22] as explained in [16].…”

BICEP/Keck data and Quadratic Gravity

“…For these reasons it is more realistic to consider CHI in some economical SM extension that can account for all observations. As a benchmark model we consider here the aνMSM one [30][31][32], which can account for all the experimentally confirmed signals of beyond-the-SM physics (neutrino oscillations and dark matter) and can solve other important issues of the SM (baryon asymmetry, the strong CP problem 3 , the metastability of the EW vacuum and inflation) at the same time.…”