Updated T2K measurements of muon neutrino and antineutrino disappearance using 1.5×10(21) protons on target

Abstract

We report measurements by the T2K experiment of the parameters θ23 and Δm2 32 governing the disappearance of muon neutrinos and antineutrinos in the three-flavor neutrino oscillation model. Utilizing the ability of the experiment to run with either a mainly neutrino or a mainly antineutrino beam, the parameters are measured separately for neutrinos and antineutrinos. Using 7.482 × 1020 POT in neutrino running mode and 7.471 × 1020 POT in antineutrino mode, T2K obtained sin2ðθ23 Þ ¼ 0.51 þ0.08 −0.07 and Δm2 32 ¼ 2.53 þ0.15 −0.13 × 10−3 eV2=c4 for neutrinos, and sin2ð¯θ 23 Þ ¼ 0.42 þ0.25 −0.07 and Δm¯ 2 32 ¼ 2.55 þ0.33 −0.27 × 10−3 eV2=c4 for antineutrinos (assuming normal mass ordering). No significant differences between the values of the parameters describing the disappearance of muon neutrinos and antineutrinos were observed.