# Consequences of $\mu$-$\tau$ reflection symmetry for $3+1$ neutrino mixing

## TL;DR

This paper explores how $-$ neutrino mixing schemes are affected by $-$ reflection symmetry, predicting specific neutrino mixing angles, CP phases, and constraints on sterile neutrino parameters, with implications for future experiments.

## Contribution

It provides a detailed analysis of $-$ reflection symmetry effects on neutrino mixing, including correlations and constraints relevant for experimental tests.

## Key findings

- Total $-$ reflection symmetry confines $ heta_{23}$ near $/4$ and $\u03b4$ near $\u00b1$.
- Partial symmetry predicts correlations between $ heta_{23}$ and $$ CP phase $$.
- Symmetry constraints tightly restrict sterile mixing angle $ heta_{34}$ and impact neutrinoless double beta decay predictions.

## Abstract

We investigate the consequences of $\mu-\tau$ reflection symmetry in presence of a light sterile neutrino for the $3+1$ neutrino mixing scheme. We discuss the implications of total $\mu-\tau$ reflection symmetry as well partial $\mu-\tau$ reflection symmetry. For the total $\mu-\tau$ reflection symmetry we find values of $\theta_{23}$ and $\delta$ remains confined near $\pi/4$ and $\pm \pi/2$ respectively. The current allowed region for $\theta_{23}$ and $\delta$ in case of inverted hierarchy lies outside the area preferred by the total $\mu-\tau$ reflection symmetry. However, interesting predictions on the neutrino mixing angles and Dirac CP violating phases are obtained considering partial $\mu-\tau$ reflection symmetry. We obtain predictive correlations between the neutrino mixing angle $\theta_{23}$ and Dirac CP phase $\delta$ and study the testability of these correlations at the future long baseline experiment DUNE. We find that while the imposition of $\mu-\tau$ reflection symmetry in the first column admit both normal and inverted neutrino mass hierarchy, demanding $\mu-\tau$ reflection symmetry for the second column excludes the inverted hierarchy. Interestingly, the sterile mixing angle $\theta_{34}$ gets tightly constrained considering the $\mu-\tau$ reflection symmetry in the fourth column. We also study consequences of $\mu-\tau$ reflection symmetry for the Majorana phases and neutrinoless double beta decay.