Speaker
Description
Sterile neutrino with masses of the keV scale is a fascinating candidate for dark matter. In particular, in the presence of significant lepton asymmetry in the standard model neutrino sector in the early universe, resonantly produced sterile neutrinos can explain all dark matter consistent with all the observational constraints. Such a large lepton asymmetry has also been suggested by recent observation of the Helium-4 abundance in the metal-poor galaxies. In this talk, we revisit the comprehensive analysis of the allowed parameter region for the resonant production scenario of sterile neutrino DM. Furthermore, we also show that such a significant lepton asymmetry can be realized within the framework of Affleck-Dine leptogenesis, which is based on minimal supersymmetric standard model. In our setup, the AD scalar with leptonic charge forms a non-topological solitons (Q-balls) that eventually dominate the energy density of the universe before decaying into a lepton-asymmetric thermal plasma.
Since the Q-ball decay process is sufficiently instantaneous, scalar-induced GWs is significantly enhanced at the sudden decay of Q-balls. In the last part of the presentation, we show the improved estimate of the GWs at such a sudden transition from Q-ball dominated era to radiation-dominated era.
This presentation is based on arXiv:2402.11902.
