Are there sterile neutrinos at the eV scale?

Area of Science:

• Particle Physics
• Neutrino Physics
• Cosmology

Background:

• Recent antineutrino flux predictions from nuclear reactors indicate a potential deficit.
• This deficit may be explained by neutrino oscillations involving sterile neutrino states.
• Existing short-baseline neutrino oscillation data present tensions and anomalies.

Purpose of the Study:

• To reanalyze global short-baseline neutrino oscillation data.
• To investigate the presence of one or two sterile neutrino states.
• To reconcile experimental results with updated reactor flux predictions.

Main Methods:

• Performed a global reanalysis of short-baseline neutrino oscillation data.
• Utilized a theoretical framework incorporating one or two sterile neutrino flavors.
• Incorporated new predictions for the antineutrino flux from nuclear reactors.

Main Results:

• A single sterile neutrino is insufficient to resolve discrepancies between reactor experiments, LSND, MiniBooNE, and null results.
• Introducing two sterile neutrinos significantly improves the global fit of oscillation data.
• The updated reactor flux predictions enhance the consistency of the two-sterile-neutrino model.

Conclusions:

• The data, particularly with new reactor flux predictions, favors a model with two sterile neutrinos.
• Sterile neutrinos offer a compelling explanation for observed anomalies in short-baseline neutrino oscillation experiments.
• Further experimental and theoretical work is needed to confirm the existence and properties of sterile neutrinos.