Sterile Neutrino Search with MicroBooNE's Electron Neutrino Disappearance Data.

Area of Science:

• Particle Physics
• Neutrino Physics
• Cosmology

Background:

• Sterile neutrinos are a minimal extension to the Standard Model, predicted to influence neutrino oscillations.
• Hints for sterile neutrinos, particularly near 1 eV mass, have accumulated over two decades from various experiments.
• Neutrino oscillations provide a sensitive probe for new physics beyond the Standard Model.

Purpose of the Study:

• To investigate the potential for sterile neutrino signals within MicroBooNE data.
• To search for electron neutrino disappearance as an indicator of sterile neutrino oscillations.
• To constrain sterile neutrino parameters using MicroBooNE's distinct analysis channels.

Main Methods:

• Utilizing data from MicroBooNE's four analysis channels to search for electron neutrino disappearance.
• Applying the Feldman-Cousins approach for significance calculation.
• Employing a simplified treatment of experimental systematic uncertainties.

Main Results:

• A 2.4σ hint for neutrino oscillations was observed in the Wire-Cell analysis channel.
• Preferred sterile neutrino parameters are sin²(2θ₁₄)=0.35$^{+0.19}_{-0.16}$ and Δm²₄₁=1.25$^{+0.74}_{-0.39}$ eV².
• The results align with existing hints from source experiments and reactor/solar neutrino data.

Conclusions:

• MicroBooNE data provides a hint consistent with sterile neutrino oscillations.
• The observed parameter space is in tension with some existing constraints but agrees with others.
• Further analysis of unanalyzed MicroBooNE data could potentially reach the >3σ sensitivity level.