November 26, 2020
The T2K experiment reports updated measurements of neutrino and antineutrino oscillations using both appearance and disappearance channels. This result comes from an exposure of 14.9 (16.4) × 1020 protons on target in neutrino (antineutrino) mode. For fits including a constraint on sin2θ13 from reactor data and assuming normal mass ordering, T2K measures sin2θ23 = 0.53+0.03-0.04 and Δ m223 = (2.45 ± 0.07) × 10-3 eV2c-4.
The Bayesian analyses show a weak preference for normal mass ordering (89% posterior probability) and the upper sin2θ23 octant (80% posterior probability), with a uniform prior probability assumed in both cases. The T2K data exclude CP conservation in neutrino oscillations at the 2σ level.
