Results from the T2K Experiment on Neutrino Mixing Including a New Far Detector μ-like Sample

Phys Rev Lett. 2025 Dec 31;135(26):261801. doi: 10.1103/gh5j-5cwv.

Abstract

We have made improved measurements of three-flavor neutrino mixing with 19.7(16.3)×10^{20} protons on target in (anti-)neutrino-enhanced beam modes. A new sample of muon-neutrino events with tagged pions has been added at the far detector, as well as new proton and photon-tagged samples at the near detector. Significant improvements have been made to the flux and neutrino interaction modeling. T2K data continue to prefer the normal mass ordering and upper octant of sin^{2}θ_{23} with a near-maximal value of the charge-parity violating phase with best-fit values in the normal ordering of δ_{CP}=-2.18_{-0.47}^{+1.22}, sin^{2}θ_{23}=0.559_{-0.078}^{+0.018} and Δm_{32}^{2}=(+2.506_{-0.052}^{+0.039})×10^{-3} eV^{2}.