New constraints on muon-neutrino to electron-neutrino transitions in MINOS

This paper reports results from a search for ${\nu }_{\mu }\to {\nu }_e$ transitions by the MINOS experiment based on a $7\times {10}^{20}$ protons-on-target exposure. Our observation of 54 candidate ${\nu }_e$ events in the far detector with a background of $49.1\pm 7.0(\mathrm{stat})\pm 2.7(\mathrm{syst})$ events predicted by the measurements in the near detector requires $2{sin}^2(2{\theta }_{13}){sin}^2{\theta }_{23}<0.12(0.20)$ at the 90% C.L. for the normal (inverted) mass hierarchy at ${\delta }_{CP}=0$. The experiment sets the tightest limits to date on the value of ${\theta }_{13}$ for nearly all values of ${\delta }_{CP}$ for the normal neutrino mass hierarchy and maximal ${sin}^2(2{\theta }_{23})$.