Speaker
Description
The dynamical generation of right-handed-neutrino (RHN) masses $M_N$ in the early Universe naturally entails the heavy scalar $\phi$, responsible for B-L symmetry breaking, whose decay in early universe leads to novel Gravitational Waves (GW) spectral shapes arising from the propagation of primordial tensor modes generated during inflation and that re-enter the horizon before or during an epoch, where the energy budget of the universe is dominated by $\phi$ or $N$, whose out of equilibrium decay releases entropy and participates in low and intermediate scale leptogenesis. We show that a characteristic simultaneous damping and knee-like features in the GW spectrum in multi-band frequency ranges would provide evidence for low-scale thermal and non-thermal leptogenesis via $\phi$ decays and subsequent RHN decays. We identify the regions of the microphysics BSM parameter space involving $\phi-N$ Yukawa $y_N$ and $M_N$, where upcoming GW detectors will be able to probe. 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 and intermediate scale leptogenesis in accord with electroweak naturalness.
