Inflationary Gravitational Wave Spectral Shapes as test for Low-Scale Leptogenesis

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Main Authors: Borboruah, Zafri A., Ghoshal, Anish, Malhotra, Lekhika, Yajnik, Urjit
Format: Preprint
Published: 2024
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author Borboruah, Zafri A.
Ghoshal, Anish
Malhotra, Lekhika
Yajnik, Urjit
author_facet Borboruah, Zafri A.
Ghoshal, Anish
Malhotra, Lekhika
Yajnik, Urjit
contents We study non-thermal resonant leptogenesis in a general setting where a heavy majoron $ϕ$ 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. A characteristic damping of the GW spectrum resulting in knee-like features would provide evidence for low-scale non-thermal leptogenesis. We explore the parameter space for the lightest right-handed neutrino mass $M_1\in[10^2,10^{14}]$ 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 majoron mass $M_ϕ$ and reheating temperature $T_ϕ$, which depends on the $ϕ-N$ Yukawa couplings $y_N$.
format Preprint
id arxiv_https___arxiv_org_abs_2405_06603
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Inflationary Gravitational Wave Spectral Shapes as test for Low-Scale Leptogenesis
Borboruah, Zafri A.
Ghoshal, Anish
Malhotra, Lekhika
Yajnik, Urjit
High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Theory
We study non-thermal resonant leptogenesis in a general setting where a heavy majoron $ϕ$ 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. A characteristic damping of the GW spectrum resulting in knee-like features would provide evidence for low-scale non-thermal leptogenesis. We explore the parameter space for the lightest right-handed neutrino mass $M_1\in[10^2,10^{14}]$ 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 majoron mass $M_ϕ$ and reheating temperature $T_ϕ$, which depends on the $ϕ-N$ Yukawa couplings $y_N$.
title Inflationary Gravitational Wave Spectral Shapes as test for Low-Scale Leptogenesis
topic High Energy Physics - Phenomenology
Cosmology and Nongalactic Astrophysics
General Relativity and Quantum Cosmology
High Energy Physics - Theory
url https://arxiv.org/abs/2405.06603