Improved Search for a Light Sterile Neutrino with the Full Configuration of the Daya Bay Experiment

TL;DR

This paper reports an improved search for light sterile neutrinos using the full Daya Bay data set, enhancing sensitivity and setting the most stringent limits to date in certain mass ranges without finding evidence of such neutrinos.

Contribution

The study provides the most stringent constraints to date on light sterile neutrino mixing parameters in the specified mass range, utilizing an expanded data set and improved analysis techniques.

Findings

No evidence of sterile neutrino mixing was observed.

Limits on mixing parameters were improved by a factor of about 2.

Constraints are the most stringent to date for certain mass ranges.

Abstract

This Letter reports an improved search for light sterile neutrino mixing in the electron antineutrino disappearance channel with the full configuration of the Daya Bay Reactor Neutrino Experiment. With an additional 404 days of data collected in eight antineutrino detectors, this search benefits from 3.6 times the statistics available to the previous publication, as well as from improvements in energy calibration and background reduction. A relative comparison of the rate and energy spectrum of reactor antineutrinos in the three experimental halls yields no evidence of sterile neutrino mixing in the $2\times10^{-4} \lesssim |\Delta m^{2}_{41}| \lesssim 0.3$ eV$^{2}$ mass range. The resulting limits on $\sin^{2}2\theta_{14}$ are improved by approximately a factor of 2 over previous results and constitute the most stringent constraints to date in the $|\Delta m^{2}_{41}| \lesssim 0.2$ eV$^{2}$ region.