T2K reports its first results in the search for $CP$ violation in neutrino oscillations using appearance and disappearance channels for neutrino- and antineutrino-mode beams. The data include all runs from January 2010 to May 2016 and comprise $7.482\times 10^{20}$ protons on target in neutrino mode, which yielded in the far detector 32 $e$-like and $135\mu$-like events, and $7.471\times 10^{20}$ protons on target in antineutrino mode, which yielded 4 $e$-like and $66\mu$-like events. Reactor measurements of ${\sin }^{2}2{\theta }_{13}$ have been used as an additional constraint. The one-dimensional confidence interval at 90% for the phase ${\delta }_{CP}$ spans the range ($-3.13$, $-0.39$) for normal mass ordering. The $CP$ conservation hypothesis (${\delta }_{CP}=0$, $\pi$) is excluded at 90% C.L.

• Received 3 January 2017

DOI:https://doi.org/10.1103/PhysRevLett.118.151801

Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.

Published by the American Physical Society