Precision measurement of neutrino oscillation parameters with 10 years of data from the NOvA experiment

Abstract

This Letter reports measurements of muon-neutrino disappearance and electron-neutrino appearance and the corresponding antineutrino processes between the two NOvA detectors in the NuMI neutrino beam. These measurements use a dataset with double the neutrino mode beam exposure that was previously analyzed, along with improved simulation and analysis techniques. A joint fit to these samples in the three-flavor paradigm results in the most precise single-experiment constraint on the atmospheric neutrino mass splitting, Δ⁢𝑚2 32=2.43⁢1+0.036 −0.034⁢(−2.47⁢9+0.036 −0.036)×10−3 eV2 if the mass ordering is normal (inverted). In both orderings, a region close to maximal mixing with sin2⁡𝜃23=0.5⁢5+0.02 −0.06 is preferred. The NOvA data show a mild preference for the normal mass ordering with a Bayes factor of 2.4 (corresponding to 70% of the posterior probability), indicating that the normal ordering is 2.4 times more probable than the inverted ordering. When incorporating a 2D Δ⁢𝑚2 32−sin2⁡2⁢𝜃13 constraint based on Daya Bay data, this preference strengthens to a Bayes factor of 6.6 (87%).