Cosmic Neutrino Decoupling and its Observable Imprints: Insights from Entropic-Dual Transport

Understand

Very different processes characterize the decoupling of neutrinos to form the cosmic neutrino background (C$\nu$B) and the much later decoupling of photons from thermal equilibrium to form the cosmic microwave background (CMB).

• The C$\nu$B emerges from the fuzzy, energy-dependent neutrinosphere and encodes the physics operating in the early universe in the temperature range $T\sim 10\,{\rm MeV}$ to $T\sim10\,{\rm keV}$.
• This is the epoch where beyond Standard Model (BSM) physics may be influential in setting the light element abundances and the necessarily distorted fossil neutrino energy spectra.
• Here we use techniques honed in extensive CMB studies to analyze the C$\nu$B as calculated in detailed neutrino energy transport and nuclear reaction simulations.