Search for a Sterile Neutrino in a 3+1 Framework using the Wire-Cell Inclusive Charged-Current νe Selection from MicroBooNE

UNSPECIFIED (2022) Search for a Sterile Neutrino in a 3+1 Framework using the Wire-Cell Inclusive Charged-Current νe Selection from MicroBooNE. Other. UNSPECIFIED.

Abstract

A search for a sterile neutrino is being carried out in the MicroBooNE experiment within the 3+1 (three flavors of active neutrinos + one flavor of sterile neutrino) framework using neutrinos from the Booster Neutrino Beam (BNB) at a baseline of about 470 m with an average neutrino energy of 800 MeV. The sensitivity of this search is built upon high performance inclusive charged-current electron neutrino (νe ) and muon neutrino (νµ ) event selections, which were utilized in the previous search for a low-energy excess (LEE) in the νe energy spectrum at MicroBooNE. In this note, we present the results of a 3+1 oscillation fit considering both νe appearance and νe /νµ disappearance. Using the first three years’ BNB data, no evidence of a light sterile neutrino was found and 95% C.L. exclusion limits were calculated in the 3+1 neutrino oscillation parameter space. Notably, the cancellation between νe disappearance and νe appearance oscillations leads to a reduced oscillation effect in the νe energy spectrum resulting in a degeneracy of the oscillation parameters. Such a degeneracy is expected to be mitigated by including the neutrino events from the off-axis Neutrino from the Main Injector (NuMI) beam. The prospect of a 3+1 oscillation analysis using both BNB and NuMI is reported and it is expected to considerably improve the sensitivity to 3+1 neutrino oscillations.