Impact of RGE-induced $ \mu-\tau $ Reflection Symmetry Breaking on the Effective Majorana Neutrino Mass in $ 0\nu\beta \beta $ Decay

Abstract

We make an attempt to study the impact of renormalization-group equations (RGE) induced $\mu-\tau$ reflection symmetry breaking on the effective Majorana neutrino mass $ |\langle m\rangle_{ee} | $ in neutrinoless double beta ($ 0\nu\beta \beta $) decay. At present, the $ 0\nu\beta \beta $ decay serves as a unique process to address the Majorana nature of massive neutrinos. The rate of such decay process depends on $ |\langle m\rangle_{ee} | $. On the other hand, $\mu-\tau$ reflection symmetry predicts $ \theta_{23} = 45^\circ$ and $ \delta = \pm 90^\circ $ together with trivial values of the Majorana CP-phases ($ \rho, \sigma $). Moreover, based on the recent global best-fit values which prefer higher octant of $ \theta_{23} $ and third quadrant of $ \delta $, it is hard to believe the exactness of such symmetry. Also, any non-trivial values of $ \rho, \sigma $ may have some significant impact on $ |\langle m\rangle_{ee} | $. In this context, we study the spontaneous breaking of the symmetry via one-loop RGE-running from a superhigh energy scale ($\Lambda_{\mu \tau} $) down to the electroweak scale ($ \Lambda_{\rm EW} $). Given the broken symmetry, we perform some systematic analysis for $ |\langle m\rangle_{ee} | $ in substantial detail. Further, we also extend this analysis for other lepton-number violating effective Majorana masses.