CP-phase effects on the effective neutrino mass $m_{ee}$ in the case of quasi-degenerate neutrinos

TL;DR

This paper explores how CP phase effects in quasi-degenerate neutrino pairs, possibly caused by active-sterile mixing, could lead to cancellations in the effective neutrino mass $m_{ee}$, impacting neutrinoless double beta decay observations.

Contribution

It introduces the idea that CP phases in quasi-degenerate neutrino pairs can cause measurable cancellations in $m_{ee}$, revealing the split states.

Findings

CP phase effects can cause cancellations in $m_{ee}$

Quasi-degenerate pairs mimic single active states in experiments

Active-sterile mixing influences neutrinoless double beta decay results

Abstract

We study the possibility that the three mass states of the ordinary active neutrinos actually split into pairs of quasi-degenerate states, with $\Delta m^2_{kk'} \sim 10^{-12}$ eV$^2$ or less, as a result of mixing of active neutrinos with sterile neutrinos. Although these quasi-degenerate pairs will look in laboratory experiment identical to single active states, the CP phase factors associated with active-sterile mixing might cause cancellations in the effective electron neutrino mass $m_{ee}$ measured in the neutrinoless double beta decay experiments thereby revealing the split nature of states.