# Imprints of a light Sterile Neutrino at DUNE, T2HK and T2HKK

## TL;DR

This paper investigates how a hypothetical light sterile neutrino affects the sensitivity of upcoming long baseline neutrino experiments (DUNE, T2HK, T2HKK) to key oscillation parameters, revealing potential reductions or changes in experimental capabilities.

## Contribution

It provides a comprehensive analysis of sterile neutrino effects on the sensitivity of multiple experiments, including combined data, and explores the dependence on sterile mixing angles.

## Key findings

- Sterile neutrinos can decrease CP violation sensitivity in these experiments.
- The impact on mass hierarchy and octant determination varies with sterile mixing angles.
- Combined analysis shows altered sensitivities compared to standard oscillation scenarios.

## Abstract

We evaluate the impact of sterile neutrino oscillations in the so-called 3+1 scenario on the proposed long baseline experiment in USA and Japan. There are two proposals for the Japan experiment which are called T2HK and T2HKK. We show the impact of sterile neutrino oscillation parameters on the expected sensitivity of T2HK and T2HKK to mass hierarchy, CP violation and octant of $\theta_{23}$ and compare it against that expected in the case of standard oscillations. We add the expected ten years data from DUNE and present the combined expected sensitivity of T2HKK+DUNE to the oscillation parameters. We do a full marginalisation over the relevant parameter space and show the effect of the magnitude of the true sterile mixing angles on the physics reach of these experiments. We show that if one assumes that the source of CP violation is the standard CP phase alone in the test case, then it appears that the expected CP violation sensitivity decreases due to sterile neutrinos. However, if we give up this assumption, then the CP sensitivity could go in either direction. The impact on expected octant of $\theta_{23}$ and mass hierarchy sensitivity is shown to depend on the magnitude of the sterile mixing angles in a nontrivial way.