Baryogenesis, primordial black holes and MHz–GHz gravitational waves

Nov 15, 2022
35 pages
Published in:
  • JCAP 02 (2023) 062
  • Published: Feb 28, 2023
e-Print:
Report number:
  • UTWI-16-2022

Citations per year

2022202320242025824191
Abstract: (IOP)
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.
Note:
  • 35 pages, 9 figures. v2: added references, corrected a typo in Eq. (3.12), version published in JCAP
  • baryon asymmetry
  • gravitational waves / theory
  • particle physics - cosmology connection
  • primordial black holes
  • black hole: primordial
  • frequency: high
  • entropy: ratio
  • fluctuation: scalar
  • baryogenesis
  • baryon number