First measurement of neutrino oscillation parameters using neutrinos and antineutrinos by NOvA

Abstract

The NOvA experiment has seen a $4.4\ensuremath{\sigma}$ signal of ${\overline{\ensuremath{\nu}}}_{e}$ appearance in a 2 GeV ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ beam at a distance of 810 km. Using $12.33\ifmmode\times\else\texttimes\fi{}{10}^{20}$ protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{e}$ candidates with a background of 10.3 and 102 ${\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}\ensuremath{\rightarrow}{\overline{\ensuremath{\nu}}}_{\ensuremath{\mu}}$ candidates. This new antineutrino data are combined with neutrino data to measure the parameters $|\mathrm{\ensuremath{\Delta}}{m}_{32}^{2}|=2.4{8}_{\ensuremath{-}0.06}^{+0.11}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }{\mathrm{eV}}^{2}/{c}^{4}$ and ${\mathrm{sin}}^{2}{\ensuremath{\theta}}_{23}$ in the ranges from (0.53--0.60) and (0.45--0.48) in the normal neutrino mass hierarchy. The data exclude most values near ${\ensuremath{\delta}}_{CP}=\ensuremath{\pi}/2$ for the inverted mass hierarchy by more than $3\ensuremath{\sigma}$ and favor the normal neutrino mass hierarchy by $1.9\ensuremath{\sigma}$ and ${\ensuremath{\theta}}_{23}$ values in the upper octant by $1.6\ensuremath{\sigma}$.