Search for a Light Sterile Neutrino at Daya Bay

TL;DR

This study used data from the Daya Bay Reactor Antineutrino Experiment to search for light sterile neutrinos, finding no evidence of their existence but setting new limits on their possible mixing parameters.

Contribution

It provides the first constraints on sterile neutrino mixing in the unexplored $10^{-3}$ to 0.1 eV$^2$ mass-squared difference range using multiple baselines.

Findings

No significant spectral distortion indicating sterile neutrinos was observed.

New limits on $ ext{sin}^2 2 heta_{14}$ were established for $10^{-3}$ to 0.1 eV$^2$.

The results are consistent with the three-flavor neutrino oscillation model.

Abstract

A search for light sterile neutrino mixing was performed with the first 217 days of data from the Daya Bay Reactor Antineutrino Experiment. The experiment's unique configuration of multiple baselines from six 2.9~GW$_{\rm th}$ nuclear reactors to six antineutrino detectors deployed in two near (effective baselines 512~m and 561~m) and one far (1579~m) underground experimental halls makes it possible to test for oscillations to a fourth (sterile) neutrino in the $10^{\rm -3}~{\rm eV}^{2} < |\Delta m_{41}^{2}| < 0.3~{\rm eV}^{2}$ range. The relative spectral distortion due to electron antineutrino disappearance was found to be consistent with that of the three-flavor oscillation model. The derived limits on $\sin^22\theta_{14}$ cover the $10^{-3}~{\rm eV}^{2} \lesssim |\Delta m^{2}_{41}| \lesssim 0.1~{\rm eV}^{2}$ region, which was largely unexplored.