Impact of CP-violation on neutrino lepton number asymmetries revisited

TL;DR

This paper investigates how CP-violation influences neutrino lepton number asymmetries, finding minimal effects on electron-neutrino asymmetries and negligible impact on mass-basis asymmetries, with implications for experimental detection.

Contribution

It provides a detailed analysis of CP-violation effects on neutrino asymmetries, highlighting their limited impact within current observational bounds.

Findings

CP-violation effects on electron-neutrino asymmetries are within BBN bounds.

Mass-basis asymmetry changes due to CP-violation are below 1%.

Effects are unlikely to be detectable in current or upcoming experiments.

Abstract

We revisit the effect of the (Dirac) CP-violating phase on neutrino lepton number asymmetries in both mass- and flavor-basis. We found that, even if there are sizable effects on muon- and tau-neutrino asymmetries, the effect on the asymmetry of electron-neutrinos is at most similar to the upper bound set by BBN for initial neutrino degeneracy parameters smaller than order unity. We also found that, for the asymmetries in mass-basis, the changes caused by CP-violation is of sub-\% level which is unlikely to be accesible neither in the current nor in the forthcoming experiments.