CP-violation search with T2K data

Abstract

The T2K experiment is a long-baseline neutrino oscillation experiment which uses ${\nu }_{\mu }$ and ${\bar{\nu }}_{\mu }$ beams to constrain CP-violating effects in a 3-flavor PMNS neutrino mixing model. Through ${\nu }_{\mu }\to {\nu }_e$ and ${\bar{\nu }}_{\mu }\to {\bar{\nu }}_e$ appearance channels, T2K is sensitive to CP-violating effects in neutrino mixing. An excess of ${\nu }_e$ candidates in the $\nu$-beam mode is observed when compared to the CP conserving cases. T2K finds a best fit value of ${\delta }_{\mathrm{CP}}=-1.97_{-0.70}^{+0.97}$ using Feldman-Cousins corrected intervals and excludes CP-conserving values of ${\delta }_{\mathrm{CP}}$ of $0$ and $\pi$ at the 90% CL. $J_{\mathrm{CP}}=0$ is also excluded at 2$\sigma$ when using a flat prior in ${\delta }_{\mathrm{CP}}$, favoring negative values.

Comments: 4 pages, 5 figures, Conference proceedings for 20th Conference on Flavor Physics and CP Violation, FPCP2022