# Search for $CP$ Violation in Neutrino and Antineutrino Oscillations by the T2K Experiment with $2.2×{10}^{21}$ Protons on Target

30 October 2018

Abstract: The T2K experiment measures muon neutrino disappearance and electron neutrino appearance in accelerator-produced neutrino and antineutrino beams. With an exposure of $14.7\left(7.6\right)×{10}^{20}$ protons on target in the neutrino (antineutrino) mode, 89 ${\nu }_{e}$ candidates and seven anti-${\nu }_{e}$ candidates are observed, while 67.5 and 9.0 are expected for ${\delta }_{CP}=0$ and normal mass ordering. The obtained $2\sigma$ confidence interval for the $CP$-violating phase, ${\delta }_{CP}$, does not include the $CP$-conserving cases (${\delta }_{CP}=0$, $\pi$). The best-fit values of other parameters are ${\mathrm{sin}}^{2}{\theta }_{23}=0.52{6}_{-0.036}^{+0.032}$ and $\Delta {m}_{32}^{2}={2.463}_{-0.070}^{+0.071}×{10}^{-3}\text{}\text{}{\mathrm{eV}}^{2}/{c}^{4}$.

Published in: Physical Review Letters 121 (2018)