Oscillation results from T2K

TL;DR

This paper reports on T2K neutrino oscillation analysis combining disappearance and appearance data, estimating key parameters and excluding certain CP-violating phase values with high confidence.

Contribution

It provides updated Bayesian estimates of neutrino oscillation parameters using combined T2K and reactor data, highlighting the hierarchy preference and CP phase constraints.

Findings

Inverted hierarchy favored with T2K data alone.

Normal hierarchy favored when combined with reactor data.

Certain CP phase values are excluded at 90% probability.

Abstract

The T2K collaboration has combined the $\nu_{\mu}$ disappearance and $\nu_e $appearance data in a three-flavor neutrino oscillation analysis. A Markov chain Monte Carlo results in estimates of the oscillation parameters and 1D 68% Bayesian credible intervals at $\delta_{CP} = 0$ as follows: $\sin^{2}\theta_{23} = 0.520^{+0.045}_{-0.050}$, $\sin^{2}\theta_{13} = 0.0454^{+ 0.011}_{-0.014}$ and $|\Delta m^{2}_{32}| = 2.57\pm0.11$, with the point of highest posterior probability in the inverted hierarchy. Recent measurements of $\theta_{13}$ from reactor neutrino experiments are combined with the T2K data resulting in the following estimates: $\sin^{2}\theta_{23} = 0.528^{+0.055}_{-0.038}$, $\sin^{2}\theta_{13} = 0.0250 \pm 0.0026$ and $|\Delta m^{2}_{32}| = 2.51\pm0.11$, with the point of highest posterior probability in the normal hierarchy. Furthermore, the data exclude values of $\delta_{CP}$ between 0.14$\pi$-0.87$\pi$ with 90% probability.