Speaker: Soumya Bhattacharyya, Tata Institute of Fundamental Research
Abstract: A supernova natively emits neutrinos and antineutrinos of all flavors with different luminosities and energy spectra. These neutrinos can undergo neutrino-neutrino forward-scattering inside the dense anisotropic interior of the star and can lead to ``Fast Neutrino Flavor Conversion''. We present the first ever theory of ``Fast Neutrino Flavor Conversion'' beyond the linear regime to show how the different neutrino flavors are brought closer to each other or in other words ``Flavor Depolarizes'' due to irreversible decoherence-like processes occurring at a Tera-Hz rate, determined by the large neutrino density. Our theory explains how depolarization happens, when does it happen, what determines the epoch and finally describes a method to calculate the extent of depolarized fluxes. This new result allows detailed implementation of flavor-dependent neutrino transport in supernova simulations and paves the way for supernova neutrino phenomenology.