# BEST potential in testing the eV-scale sterile neutrino explanation of reactor antineutrino anomalies

## TL;DR

The BEST experiment aims to test the sterile neutrino explanation for reactor and Gallium anomalies, with potential to provide significant evidence if results align with previous findings.

## Contribution

This study evaluates BEST's sensitivity to eV-scale sterile neutrinos and its potential to confirm anomalies through combined analysis of existing data.

## Key findings

- Moderate sensitivity to sterile neutrino parameter space.
- Neutrino-4 results are consistent with Gallium anomaly.
- Potential for over 5σ evidence if BEST confirms Neutrino-4.

## Abstract

Baksan Experiment on Sterile Neutrino (BEST) is presently at the stage of production of the artificial neutrino source Cr-51, the gallium exposure will start in July and proceed for three months. While aiming specifically at investigating the Gallium neutrino anomaly (SAGE and GALLEX experiments), BEST can do more and it is tempting to estimate its ability in testing sterile neutrino explanation of antineutrino (reactor) anomalies. We observe a moderate sensitivity to the region in model parameter space (sterile neutrino mass and mixing with active electron neutrino) outlined by the old reactor antineutrino anomaly and the best fit of DANSS experiment, while the Neutrino-4 favorite region falls right in the BEST ballpark. In particular, by analyzing SAGE+GALLEX and Neutrino-4 $\chi^2$ distributions we find that Neutrino-4 results are fully consistent with the Gallium anomaly, the significance of the combined anomaly almost reaches 4$\sigma$ level. If the BEST confirms the Neutrino-4 results, the joint analysis will indicate more than 5$\sigma$ evidence for the sterile neutrino of eV-scale mass.