Improved measurement of neutrino oscillation parameters by the NOvA experiment

We present new ${\nu }_{\mu }\to {\nu }_{e}$, ${\nu }_{\mu }\to {\nu }_{\mu }$, ${\overline{\nu }}_{\mu }\to {\overline{\nu }}_{e}$, and ${\overline{\nu }}_{\mu }\to {\overline{\nu }}_{\mu }$ oscillation measurements by the NOvA experiment, with a 50% increase in neutrino-mode beam exposure over the previously reported results. The additional data, combined with previously published neutrino and antineutrino data, are all analyzed using improved techniques and simulations. A joint fit to the ${\nu }_{e}$, ${\nu }_{\mu }$, ${\overline{\nu }}_{e}$, and ${\overline{\nu }}_{\mu }$ candidate samples within the 3-flavor neutrino oscillation framework continues to yield a best-fit point in the normal mass ordering and the upper octant of the ${\theta }_{23}$ mixing angle, with $\Delta {m}_{32}^{2}=\left(2.41±0.07\right)×{10}^{-3}\text{}\text{}{\mathrm{eV}}^{2}$ and ${\mathrm{sin}}^{2}{\theta }_{23}=0.5{7}_{-0.04}^{+0.03}$. The data disfavor combinations of oscillation parameters that give rise to a large asymmetry in the rates of ${\nu }_{e}$ and ${\overline{\nu }}_{e}$ appearance. This includes values of the charge parity symmetry (CP) violating phase in the vicinity of ${\delta }_{\mathrm{CP}}=\pi /2$ which are excluded by $>3\sigma $ for the inverted mass ordering, and values around ${\delta }_{\mathrm{CP}}=3\pi /2$ in the normal ordering which are disfavored at $2\sigma $ confidence.