Updated T2K measurements of muon neutrino and antineutrino disappearance using 1.5e21 protons on target

Abstract

We report measurements by the T2K experiment of the parameters ${\theta }_{23}$ and $\Delta m_{32}^2$ 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 $7.482\times 10^{20}$ POT in neutrino running mode and $7.471\times 10^{20}$ POT in antineutrino mode, T2K obtained, ${\sin }^2({\theta }_{23})=0.51_{-0.07}^{+0.08}$ and $\Delta m_{32}^2=2.53_{-0.13}^{+0.15}\times 10^{-3}$eV${}^2$/c${}^4$ for neutrinos, and ${\sin }^2({\overline{\theta }}_{23})=0.42_{-0.07}^{+0.25}$ and ${\Delta {\overline{m}}^2}_{32}=2.55_{-0.27}^{+0.33}\times 10^{-3}$eV${}^2$/c${}^4$ 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.

8 pages, 2 figures