Effect of Non Unitarity on Neutrino Mass Hierarchy determination at DUNE, NO$\nu$A and T2K

TL;DR

This paper investigates how non-unitarity in the leptonic mixing matrix reduces the ability of DUNE, NOvA, and T2K experiments to determine the neutrino mass hierarchy, highlighting the impact of new physics.

Contribution

It provides a detailed analysis of how non-unitarity affects the mass hierarchy sensitivity of major long baseline neutrino experiments, including oscillation probabilities and discovery potential.

Findings

Mass hierarchy sensitivity decreases with non-unitarity.

DUNE's ability to discriminate hierarchies is significantly suppressed.

The extent of sensitivity loss varies among DUNE, NOvA, and T2K.

Abstract

The neutrino mass ordering is one of the principal unknowns in the neutrino sector. Long baseline neutrino experiments have the potential of resolving this issue as they are sensitive to large matter effects. The superbeam experiment DUNE is one of the most promising candidates to study the neutrino mass hierarchy, along with NO$\nu$A and T2K. But in the presence of non unitarity of the leptonic mixing matrix, the capability of such experiments to discriminate between the two hierarchies gets suppressed. The mass hierarchy sensitivity of DUNE decreases in the presence of new physics. In this paper we analyze the origin and extent of this loss of sensitivity at the level of oscillation probabilities, events, mass hierarchy sensitivity and the discovery reach of DUNE, NO$\nu$A and T2K.