New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter θ23. Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to 6.57 × 1020 protons on target, T2K has fit the energy-dependent νμ oscillation probability to determine oscillation parameters. The 68% confidence limit on sin2(θ23) is 0.514-0.056+0.055 (0.511 ± 0.055), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is Δm322 = (2.51 × 0.10) × 10-3 eV2/c4 (inverted hierarchy: Δm13 = (2.48 ± 0.10) × 10-3 eV2/c4). Adding a model of multinucleon interactions that affect neutrino energy reconstruction is found to produce only small biases in neutrino oscillation parameter extraction at current levels of statistical uncertainty.
ASJC Scopus subject areas
- Physics and Astronomy(all)