A Combined $\nu_\mu \to \nu_e$ and $\bar\nu_\mu \to \bar\nu_e$ Oscillation Analysis of the MiniBooNE Excesses

TL;DR

The MiniBooNE experiment observed a significant excess of electron neutrino and antineutrino events, supporting the possibility of neutrino oscillations involving sterile neutrinos in the 0.01 to 1.0 eV^2 mass-squared difference range.

Contribution

This study provides a combined analysis of neutrino and antineutrino appearance data, strengthening evidence for oscillations consistent with sterile neutrinos.

Findings

Observed a 3.8 sigma excess of events.

Data favor oscillations in the 0.01 to 1.0 eV^2 range.

Background-only fit has very low probability compared to oscillation hypothesis.

Abstract

The MiniBooNE experiment at Fermilab reports results from an analysis of the combined $\nu_e$ and $\bar \nu_e$ appearance data from $6.46 \times 10^{20}$ protons on target in neutrino mode and $11.27 \times 10^{20}$ protons on target in antineutrino mode. A total excess of $240.3 \pm 34.5 \pm 52.6$ events ($3.8 \sigma$) is observed from combining the two data sets in the energy range $200<E_\nu^{QE}<1250$ MeV. In a combined fit for CP-conserving $\nu_\mu \rightarrow \nu_e$ and $\bar{\nu}_{\mu}\rightarrow\bar{\nu}_e$ oscillations via a two-neutrino model, the background-only fit has a $\chi^2$-probability of 0.03% relative to the best oscillation fit. The data are consistent with neutrino oscillations in the $0.01 < \Delta m^2 < 1.0$ eV$^2$ range and with the evidence for antineutrino oscillations from the Liquid Scintillator Neutrino Detector (LSND).