Baryogenesis, Primordial Black Holes and MHz-GHz Gravitational Waves

Abstract

Gravitational waves (GWs) in the MHz -GHz frequency range are motivated by a host of early Universe phenomena such as oscillons, preheating, and cosmic strings. We point out that baryogenesis too serves as a motivation to probe GWs in this frequency range. The connection is through primordial black holes (PBHs): on the one hand, PBHs induce baryogenesis by Hawking evaporating into a species that has baryon number and CP violating decays; on the other, PBHs induce GWs through second order effects when the scalar fluctuations responsible for their formation re-enter the horizon. We describe the interplay of the parameters responsible for successful baryogenesis on the plane of the strain and frequency of the induced GWs, being careful to delineate regimes where PBH domination or washout effects occur. We provide semi-analytic scalings of the GW strain with the baryon number to entropy ratio and other parameters important for baryogenesis. Along the way, we sketch a solution to the dark matter-baryogenesis coincidence problem with two populations of PBHs, which leads to a double-peaked GW signal. Our results underscore the importance of probing the ultra high frequency GW frontier.

Primordial black holes in loop quantum cosmology: the effect on the threshold

“…Indicatively, we mention here that these ultra-light PBHs can trigger early PBH-matter dominated eras [20,21,111] before BBN and produce the DM relic abundance and the hot standard model plasma [112] reheating in this way the Universe through their evaporation [113]. Furthermore, they can account for the Hubble tension through the injection to the primordial plasma of light dark radiation degrees of freedom [114,115] while at the same time they can produce naturally the baryon asymmetry through CP violating outof-equilibrium decays of their Hawking evaporation products [116][117][118]. Consequently, one can constrain the above mentioned observational/phenomenological signatures by studying PBH formation within the context of LQG while vice-versa given the above mentioned phenomenology one can constrain the Barbero-Immirzi parameter γ which is the fundamental parameter within LQG.…”

Primordial black holes and scalar-induced gravitational waves from the perturbations on the inflaton potential in peak theory

“…(3) As shown in Figs. 1 and 2, the PBHs of 10 −17 M or 10 −13 M can compose all DM with f PBH (M ) ∼ 1, and their relevant SIGW spectra Ω GW (f ) are intense enough to reach the sensitivity curves of the next-generation GW detectors like LISA [87][88][89][90] and BBO [91,92], without touching the current constraint from aLIGO. Moreover, for the PBH of 30 M , from the middle and right panels in Fig.…”