Sterile Neutrino Searches with MicroBooNE: Electron Neutrino Disappearance

Abstract

A sterile neutrino is a well motivated minimal new physics model that leaves an imprint in neutrino oscillations. Over the last two decades, a number of hints pointing to a sterile neutrino have emerged, many of which are pointing near $m_4\sim1$ eV. Here we show how MicroBooNE data can be used to search for electron neutrino disappearance using each of their four analysis channels. We find a hint for oscillations with the highest single channel significance of $2.4\sigma$ (using the Feldman-Cousins approach) coming from the Wire-Cell analysis and a simplified treatment of the experimental systematics. The preferred parameters are $\sin^2(2\theta_{14})=0.35^{+0.19}_{-0.16}$ and $\Delta m^2_{41}=1.25^{+0.74}_{-0.39}$ eV$^2$. This region of parameter space is in good agreement with existing hints from source experiments, is at a similar frequency but higher mixing than indicated by reactor anti-neutrinos, and is at the edge of the region allowed by solar neutrino data. Existing unanalyzed data from MicroBooNE could increase the sensitivity to the $>3\sigma$ level.