Improved measurement of neutrino oscillation parameters by the NOvA experiment

We present new ν μ → ν e , ν μ → ν μ , ¯ ν μ → ¯ ν e , and ¯ ν μ → ¯ ν μ 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 ν e , ν μ , ¯ ν e , and ¯ ν μ 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 θ 23 mixing angle, with Δ m 2 32 ¼ ð 2 . 41 (cid:2) 0 . 07 Þ × 10 − 3 eV 2 and sin 2 θ 23 ¼ 0 . 57 þ 0 . 03 − 0 . 04 . The data disfavor combinations of oscillation parameters that give rise to a large asymmetry in the rates of ν e and ¯ ν e appearance. This includes values of the charge parity symmetry (CP) violating phase in the vicinity of δ CP ¼ π = 2 which are excluded by > 3 σ for the inverted mass ordering, and values around δ CP ¼ 3 π = 2 in the normal ordering which are disfavored at 2 σ confidence.