Improved search for muon-neutrino to electron-neutrino oscillations in MINOS

TL;DR

This paper reports an improved search for muon-neutrino to electron-neutrino oscillations in the MINOS experiment, providing tighter constraints on oscillation parameters and disfavoring the zero theta13 hypothesis at 89% confidence.

Contribution

The study presents an enhanced analysis method and increased data exposure, leading to more stringent limits on neutrino oscillation parameters compared to previous results.

Findings

Upper limits on oscillation parameters at 90% CL

Disfavoring of theta13=0 hypothesis at 89% CL

Best-fit oscillation parameter values with uncertainties

Abstract

We report the results of a search for $\nu_{e}$ appearance in a $\nu_{\mu}$ beam in the MINOS long-baseline neutrino experiment. With an improved analysis and an increased exposure of $8.2\times10^{20}$ protons on the NuMI target at Fermilab, we find that $2\sin^2(\theta_{23})\sin^2(2\theta_{13})<0.12\ (0.20)$ at 90% confidence level for $\delta\mathord{=}0$ and the normal (inverted) neutrino mass hierarchy, with a best fit of $2\sin^2(\theta_{23})\sin^2(2\theta_{13})\,\mathord{=}\,0.041^{+0.047}_{-0.031}\ (0.079^{+0.071}_{-0.053})$. The $\theta_{13}\mathord{=}0$ hypothesis is disfavored by the MINOS data at the 89% confidence level.