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

Abstract

The NOvA experiment has seen a 4.4σ signal of ¯νe appearance in a 2 GeV ¯νμ beam at a distance of 810 km. Using 12.33 × 1020 protons on target delivered to the Fermilab NuMI neutrino beamline, the experiment recorded 27 ¯νμ → ¯νe candidates with a background of 10.3 and 102 ¯νμ → ¯νμ candidates. This new antineutrino data are combined with neutrino data to measure the parameters jΔm2 32j ¼ 2.48þ0.11 −0.06 × 10−3 eV2=c4 and sin2 θ23 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 δCP ¼ π=2 for the inverted mass hierarchy by more than 3σ and favor the normal neutrino mass hierarchy by 1.9σ and θ23 values in the upper octant by 1.6σ.