MiniBooNE and MicroBooNE Combined Fit to a 3+1 Sterile Neutrino Scenario

TL;DR

This paper analyzes combined MiniBooNE and MicroBooNE data within a 3+1 sterile neutrino model, finding a preference for sterile neutrino oscillations with specific parameters and significant statistical significance.

Contribution

It provides the first combined fit of MiniBooNE and MicroBooNE data in a 3+1 sterile neutrino scenario, identifying best-fit parameters and statistical preference over no-oscillation.

Findings

Data favor the 3+1 sterile neutrino model over no-oscillation.

Best-fit parameters indicate a Δm² around 0.3 eV² and large mixing angles.

Statistical significance of the preference exceeds 3 sigma.

Abstract

This letter presents the results from the MiniBooNE experiment within a full "3+1" scenario where one sterile neutrino is introduced to the three-active-neutrino picture. In addition to electron-neutrino appearance at short-baselines, this scenario also allows for disappearance of the muon-neutrino and electron-neutrino fluxes in the Booster Neutrino Beam, which is shared by the MicroBooNE experiment. We present the 3+1 fit to the MiniBooNE electron-(anti)neutrino and muon-(anti)neutrino data alone, and in combination with MicroBooNE electron-neutrino data. The best-fit parameters of the combined fit with the exclusive CCQE analysis (inclusive analysis) are $\Delta m^2 = 0.29 eV^2 (0.33 eV^2)$, $|U_{e4}|^2 = 0.016 (0.500)$, $|U_{\mu 4}|^2 = 0.500 (0.500)$, and $\sin^2(2\theta_{\mu e})=0.0316 (1.0)$. Comparing the no-oscillation scenario to the 3+1 model, the data prefer the 3+1 model with a $\Delta \chi^2/\text{dof} = 24.7 / 3 (17.3 / 3)$, a $4.3\sigma (3.4\sigma)$ preference assuming the asymptotic approximation given by Wilks' theorem.