Inflationary Gravitational Wave Spectral Shapes as test for Low-Scale Leptogenesis
arxiv(2024)
Abstract
We study thermal and non-thermal resonant leptogenesis in a general setting
where a heavy scalar ϕ decays to right-handed neutrinos (RHNs) whose
further out-of-equilibrium decay generates the required lepton asymmetry.
Domination of the energy budget of the Universe by the ϕ or the RHNs
alters the evolution history of the primordial gravitational waves (PGW), of
inflationary origin, which re-enter the horizon after inflation, modifying the
spectral shape. The decays of ϕ and RHNs release entropy into the early
Universe while nearly degenerate RHNs facilitate low and intermediate scale
leptogenesis. We show that depending on the coupling y_R of ϕ to
radiation species, RHNs can achieve thermal abundance before decaying, which
gives rise to thermal leptogenesis. A characteristic damping of the GW spectrum
resulting in two knee-like features or one knee-like feature would provide
evidence for low-scale thermal and non-thermal leptogenesis respectively. We
explore the parameter space for the lightest right-handed neutrino mass
M_1∈[10^2,10^14] GeV and washout parameter K that depends on the
light-heavy neutrino Yukawa couplings λ, in the weak (K < 1) and
strong (K > 1) washout regimes. The resulting novel features compatible with
observed baryon asymmetry are detectable by future experiments like LISA and
ET. By estimating signal-to-noise ratio (SNR) for upcoming GW experiments, we
investigate the effect of the scalar mass M_ϕ and reheating temperature
T_ϕ, which depends on the ϕ-N Yukawa couplings y_N.
MoreTranslated text
AI Read Science
Must-Reading Tree
Example
![](https://originalfileserver.aminer.cn/sys/aminer/pubs/mrt_preview.jpeg)
Generate MRT to find the research sequence of this paper
Chat Paper
Summary is being generated by the instructions you defined