Sensitivity of medium-baseline reactor neutrino mass-hierarchy experiments to nonstandard interactions

TL;DR

This paper investigates how nonstandard interactions at source and detector influence medium-baseline reactor neutrino experiments, affecting their ability to determine neutrino mass hierarchy and interpret observed spectra.

Contribution

It extends current models by including nonstandard flavor structures in source and detector interactions and analyzes their impact on mass hierarchy sensitivity.

Findings

Nonstandard interactions can alter the observed neutrino spectrum at 50 km baseline.

Sensitivity to nonstandard interactions can be improved with better mixing parameter measurements.

Nonstandard interactions can either enhance or suppress mass hierarchy sensitivity depending on phase parameters.

Abstract

We explore the impact of nonstandard interactions at source and detector on the interpretation of reactor electron neutrino disappearance experiments with short- and medium-baseline designs. We use the constraints from the recent results from short-baseline experiments and generalize current estimates of medium-baseline event rates to include charged current interactions at source and detector with standard Lorentz structure but with nonstandard flavor structure. We find that the average spectrum of observed events at a baseline of 50 km, in the middle of the currently favored region, provides a probe of new interactions. We show that an improvement in sensitivity to nonstandard interactions is possible if combined with improved precision of input mixing parameters in independent experiments, despite ambiguity in interpretation of medium-baseline data. We show that nonstandard interactions can enhance or suppress the sensitivity of experiments to the mass hierarchy, depending on the phases of the parameters and the CP-violating phase in the standard three-neutrino mixing picture.