Precise Measurement of the Neutrino Mixing Parameter θ23 from Muon Neutrino Disappearance in an Off-Axis Beam

Le résumé fourni par la source

New data from the T2K neutrino oscillation experiment produce the most precise measurement of the neutrino mixing parameter ${\ensuremath{\theta}}_{23}$. Using an off-axis neutrino beam with a peak energy of 0.6 GeV and a data set corresponding to $6.57\ifmmode\times\else\texttimes\fi{}1{0}^{20}$ protons on target, T2K has fit the energy-dependent ${\ensuremath{\nu}}_{\ensuremath{\mu}}$ oscillation probability to determine oscillation parameters. The 68% confidence limit on ${\mathrm{sin}}^{2}({\ensuremath{\theta}}_{23})$ is $0.51{4}_{\ensuremath{-}0.056}^{+0.055}$ ($0.511\ifmmode\pm\else\textpm\fi{}0.055$), assuming normal (inverted) mass hierarchy. The best-fit mass-squared splitting for normal hierarchy is $\mathrm{\ensuremath{\Delta}}{m}_{32}^{2}=(2.51\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}\text{ }\text{ }{\mathrm{eV}}^{2}/{c}^{4}$ (inverted hierarchy: $\mathrm{\ensuremath{\Delta}}{m}_{13}^{2}=(2.48\ifmmode\pm\else\textpm\fi{}0.10)\ifmmode\times\else\texttimes\fi{}\phantom{\rule{0ex}{0ex}}{10}^{\ensuremath{-}3}\text{ }\text{ }{\mathrm{eV}}^{2}/{c}^{4}$). 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.

Ce résumé expose les affirmations des auteurs. BNTIC ne l’interprète pas comme une validation indépendante des résultats.