Probing neutrino physics with a self-consistent treatment of the weak decoupling, nucleosynthesis, and photon decoupling epochs

TL;DR

This paper develops a comprehensive model of early universe epochs to better constrain neutrino physics using precise cosmological measurements, exploring implications for dark radiation, neutrino mass, and sterile neutrinos.

Contribution

It introduces a self-consistent approach linking weak decoupling, nucleosynthesis, and photon decoupling to improve constraints on neutrino sector physics.

Findings

Constraints on dark radiation from CMB and element abundances

Limits on neutrino rest mass and sum of neutrino masses

Implications for sterile neutrino scenarios

Abstract

We show that a self-consistent and coupled treatment of the weak decoupling, big bang nucleosynthesis, and photon decoupling epochs can be used to provide new insights and constraints on neutrino sector physics from high-precision measurements of light element abundances and cosmic microwave background observables. Implications of beyond-standard-model physics in cosmology, especially within the neutrino sector, are assessed by comparing predictions against five observables: the baryon energy density, helium abundance, deuterium abundance, effective number of neutrinos, and sum of the light neutrino mass eigenstates. We give examples for constraints on dark radiation, neutrino rest mass, lepton numbers, and scenarios for light and heavy sterile neutrinos.