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

Area of Science:

• Particle Physics
• Neutrino Physics

Background:

• Neutrino oscillations suggest neutrinos have mass.
• The existence of sterile neutrinos is hypothesized but not experimentally confirmed.

Purpose of the Study:

• To search for evidence of a sub-eV sterile neutrino mixing with active neutrinos.
• To set exclusion limits on sterile neutrino mixing parameters.

Main Methods:

• Analysis of a large dataset (5.55×10^6 candidates) of reactor antineutrinos from the Daya Bay experiment.
• Utilized inverse beta-decay interactions followed by neutron capture on gadolinium.
• Employed Feldman-Cousins and CLs statistical methods for exclusion limits.

Main Results:

• No significant oscillation signal indicative of a sub-eV sterile neutrino was observed.
• Exclusion limits were placed on sterile neutrino mixing, specifically sin^2(2θ14) > 0.01 for 0.01 eV^2 ≲ |Δm41^2| ≲ 0.1 eV^2.
• Achieved world-leading constraints on light sterile neutrino mixing in the range 2×10^-4 eV^2 ≲ |Δm41^2| ≲ 0.2 eV^2.

Conclusions:

• The results exclude a significant parameter space for light sterile neutrino mixing.
• The experiment provides the most stringent constraints to date on sterile neutrino oscillations in a specific mass range.