The dynamical generation of right-handed-neutrino (RHN) masses in the early Universe naturally entails the formation of cosmic strings that give rise to an observable signal in gravitational waves (GWs). Here, we show that a characteristic break in the GW spectrum would provide evidence for a new stage in the cosmological expansion history and a suppression of the RHN mass scale compared to the scale of spontaneous symmetry breaking. The detection of such a spectral feature would thus represent a novel and unique possibility to probe the physics of RHN mass generation in regions of parameter space that allow for low-scale leptogenesis in accord with electroweak naturalness.
@article{arxiv.2004.02889,
title = {Fingerprint of Low-Scale Leptogenesis in the Primordial Gravitational-Wave Spectrum},
author = {Simone Blasi and Vedran Brdar and Kai Schmitz},
journal= {arXiv preprint arXiv:2004.02889},
year = {2020}
}
Comments
8 pages, 2 figures, 1 table. v2: updated references, matches version published in Phys. Rev. Research