Stability of Neutrino Mass Degeneracy

TL;DR

This paper investigates the stability of neutrino mass degeneracy under radiative corrections, highlighting that opposite CP eigenstates with maximal mixing are stable due to an underlying symmetry.

Contribution

It identifies conditions under which neutrino mass degeneracy remains stable, emphasizing the role of CP eigenstates and symmetries in neutrino mass models.

Findings

Degenerate neutrino masses are unstable unless they are opposite CP eigenstates.

Maximal mixing ($45^ extdegree$) stabilizes neutrino mass degeneracy.

Symmetry considerations explain the stability of certain neutrino mass configurations.

Abstract

Two neutrinos of Majorana masses $m_{1,2}$ with mixing angle $\theta$ are unstable against radiative corrections in the limit $m_1 = m_2$, but are stable for $m_1 = -m_2$ (i.e. opposite CP eigenstates) with $\theta = 45^\circ$ which corresponds to an additional symmetry.