Speaker
Description
Neutrinos are the known portal to the beyond-Standard Model physics. Any new self-interaction among the active neutrinos other than the electroweak interaction gives rise to rich phenomenology in the cosmological observables. In this talk, I'll present a novel scenario where the active neutrinos are partially converted into a hidden sector radiation in the early Universe. This hidden sector radiation particles behave like neutrinos and can effectively mimic the cosmology of self-interacting neutrinos. This mechanism simultaneously relaxes the self-interaction bounds on dark radiation and the bound on neutrino mass, thereby opening up new parameter space for nonstandard neutrino cosmology. I'll also show the implications of the latest JWST observation data on neutrino self-interaction models.