The fate of hints: updated global analysis of three-flavor neutrino oscillations

TL;DR

This paper provides an updated global analysis of three-flavor neutrino oscillations, showing reduced hints for neutrino mass ordering and refined constraints on oscillation parameters based on recent experimental data.

Contribution

It offers the latest combined analysis of neutrino oscillation data, clarifying the current status of mass ordering and CP violation hints with new experimental results.

Findings

Normal mass ordering is only favored at 1.6σ.

CP conserving value δ_CP=180° is within 0.6σ of best fit.

Updated oscillation parameter ranges and leptonic Jarlskog determinant.

Abstract

Our herein described combined analysis of the latest neutrino oscillation data presented at the Neutrino2020 conference shows that previous hints for the neutrino mass ordering have significantly decreased, and normal ordering (NO) is favored only at the $1.6\sigma$ level. Combined with the $\chi^2$ map provided by Super-Kamiokande for their atmospheric neutrino data analysis the hint for NO is at $2.7\sigma$. The CP conserving value $\delta_\text{CP} = 180^\circ$ is within $0.6\sigma$ of the global best fit point. Only if we restrict to inverted mass ordering, CP violation is favored at the $\sim 3\sigma$ level. We discuss the origin of these results - which are driven by the new data from the T2K and NOvA long-baseline experiments -, and the relevance of the LBL-reactor oscillation frequency complementarity. The previous $2.2\sigma$ tension in $\Delta m^2_{21}$ preferred by KamLAND and solar experiments is also reduced to the $1.1\sigma$ level after the inclusion of the latest Super-Kamiokande solar neutrino results. Finally we present updated allowed ranges for the oscillation parameters and for the leptonic Jarlskog determinant from the global analysis.