First joint oscillation analysis of Super-Kamiokande atmospheric and T2K accelerator neutrino data

TL;DR

This paper reports a joint analysis of atmospheric and accelerator neutrino data from Super-Kamiokande and T2K, providing new insights into neutrino oscillation parameters, including a mild exclusion of CP-conservation and a preference for normal mass ordering.

Contribution

It presents the first combined oscillation analysis of atmospheric and beam neutrino data with a shared interaction model and correlated systematic uncertainties.

Findings

1.9σ exclusion of CP-conservation

Preference for normal mass ordering

Consistent results between datasets

Abstract

The Super-Kamiokande and T2K collaborations present a joint measurement of neutrino oscillation parameters from their atmospheric and beam neutrino data. It uses a common interaction model for events overlapping in neutrino energy and correlated detector systematic uncertainties between the two datasets, which are found to be compatible. Using 3244.4 days of atmospheric data and a beam exposure of $19.7(16.3) \times 10^{20}$ protons on target in (anti)neutrino mode, the analysis finds a 1.9$\sigma$ exclusion of CP-conservation (defined as $J_{CP}=0$) and a preference for the normal mass ordering.