Search for a Sub-eV Sterile Neutrino using Daya Bay's Full Dataset

Abstract

<p>This Letter presents results of a search for the mixing of a sub-eV sterile neutrino with three active neutrinos based on the full data sample of the Daya Bay Reactor Neutrino Experiment, collected during 3158 days of detector operation, which contains 5.55×106 reactor ¯𝜈𝑒 candidates identified as inverse beta-decay interactions followed by neutron capture on gadolinium. The analysis benefits from a doubling of the statistics of our previous result and from improvements of several important systematic uncertainties. No significant oscillation due to mixing of a sub-eV sterile neutrino with active neutrinos was found. Exclusion limits are set by both Feldman-Cousins and CLs methods. Light sterile neutrino mixing with sin2⁡2⁢𝜃14≳0.01 can be excluded at 95% confidence level in the region of 0.01 eV2≲|Δ⁢𝑚241|≲0.1 eV2. This result represents the world-leading constraints in the region of 2×10−4 eV2≲|Δ⁢𝑚241|≲0.2 eV2.<br></p>