Constraints on the lepton asymmetry from DESI DR2 BAO data

Abstract

It is important to explore the potential existence of lepton asymmetry in the neutrino sector. Conducting a joint analysis of DESI DR2 BAO data and \emph{Planck} 2018 CMB data, we obtain the upper limits on the neutrino degeneracy parameter, i.e., $\xi<0.56$ for the normal mass hierarchy while $\xi<0.62$ for the inverted mass hierarchy, at 95\% confidence level. Considering the influence of the dynamical dark energy, we find that these upper limits remain to be robust. This work may provide helpful implications for model buildings of the matter-antimatter asymmetry in the universe.