Resurrection of large lepton number asymmetries from neutrino flavor oscillations

TL;DR

This paper demonstrates through numerical solutions that large lepton number asymmetries can persist despite neutrino flavor oscillations, remaining consistent with Big Bang Nucleosynthesis constraints.

Contribution

It provides a numerical analysis showing that significant lepton asymmetries are compatible with neutrino oscillations and BBN, challenging previous assumptions.

Findings

Large lepton asymmetries can survive neutrino oscillations.

Neutrino flavor mixing does not necessarily erase lepton asymmetries.

Compatibility with Big Bang Nucleosynthesis constraints is maintained.

Abstract

We numerically solve the evolution equations of neutrino three-flavor density matrices, and show that, even if neutrino oscillations mix neutrino flavors, large lepton number asymmetries are still allowed in certain limits by Big Bang Nucleosynthesis (BBN).