Probing non-unitarity of the PMNS matrix in P2SO and comparison with DUNE

TL;DR

This paper compares the sensitivity of P2SO and DUNE neutrino experiments to non-unitarity in the leptonic mixing matrix, highlighting their complementary strengths and the impact on neutrino parameter measurements.

Contribution

It provides a model-independent analysis of how P2SO and DUNE can constrain non-unitarity parameters and their effects on neutrino oscillation measurements.

Findings

DUNE better constrains $oldsymbol{\alpha_{11}}$ and $oldsymbol{|\alpha_{21}|}$.

P2SO has superior sensitivity to $oldsymbol{\alpha_{22}}$ and $oldsymbol{\alpha_{33}}$.

Both experiments can improve current bounds on specific non-unitarity parameters.

Abstract

We compare the sensitivity of the upcoming long-baseline neutrino experiments Protvino to Super-ORCA (P2SO) and the Deep Underground Neutrino Experiment (DUNE) to non-unitarity (NU) of the leptonic mixing matrix in a model-independent framework. NU can arise in theories beyond the Standard Model that include heavy neutral leptons. These effects can modify neutrino oscillation probabilities and introduce new sources of CP violation, which may affect precision measurements of neutrino parameters. We find that DUNE provides stronger bounds on $\alpha_{11}$ and $|\alpha_{21}|$, while P2SO shows better sensitivity to $\alpha_{22}$ and $\alpha_{33}$, mainly due to its longer baseline and stronger matter effects. Our results show that DUNE (P2SO) will be able to improve the current bounds of $\alpha_{11}$ ($\alpha_{33}$). We further examine correlations with standard oscillation parameters and quantify the impact of NU on mass hierarchy, octant, and CP-violation sensitivities. Our results show that these sensitivities depend upon NU in a non-trivial way interconnecting the parameter degeneracies and matter effects. Our results demonstrate the complementarity of P2SO and DUNE in probing NU and show that NU can significantly influence next-generation precision oscillation studies.