Sterile Neutrinos: Reactor Experiments

TL;DR

Nuclear reactor experiments are used to investigate the reactor antineutrino anomaly, which may indicate oscillations to sterile neutrinos, potentially revealing new physics beyond the Standard Model.

Contribution

This paper reviews the use of reactor experiments to search for sterile neutrinos and discusses the implications of observed anomalies for new physics.

Findings

Reactor experiments observe a 6% deficit in antineutrino flux.

The anomaly is statistically significant at 2.5σ.

Potential evidence for sterile neutrino oscillations.

Abstract

Nuclear reactors are strong, pure and well localized sources of electron antineutrinos with energies in the few MeV range. Therefore they provide a suitable environment to study neutrino properties, in particular neutrino oscillation parameters. Recent predictions of the expected antineutrino flux at nuclear reactors are about 6% higher than the average rate measured in different experiments. This discrepancy, known as the reactor antineutrino anomaly, is significant at the 2.5{\sigma} level. Several new experiments are searching for the origin of this observed neutrino deficit. One hypothesis to be tested is an oscillation to another neutrino state. In a three flavor model reactor neutrinos do not oscillate at baselines below 100 m. Hence, if such an oscillation is observed, it would imply the existence of at least one light sterile neutrino state not participating in weak interactions. Such a discovery would open the gate for new physics beyond the Standard Model.