Updated fit to three neutrino mixing: status of leptonic CP violation

TL;DR

This paper provides an updated global analysis of three-neutrino oscillation data, constraining mixing parameters and CP violation, with implications for understanding leptonic CP violation and neutrino mixing angles.

Contribution

It offers the most recent combined analysis of neutrino oscillation data, including stability checks and insights into CP violation and mixing angle octants.

Findings

Maximal leptonic Jarlskog invariant is approximately 0.033.

Favored CP phase around 3π/2, disfavoring π/2.

Tensions exist regarding the octant of θ23 and CP phase δ_CP.

Abstract

We present a global analysis of solar, atmospheric, reactor and accelerator neutrino data in the framework of three-neutrino oscillations based on data available in summer 2014. We provide the allowed ranges of the six oscillation parameters and show that their determination is stable with respect to uncertainties related to reactor neutrino and solar neutrino flux predictions. We find that the maximal possible value of the Jarlskog invariant in the lepton sector is $0.0329 \pm 0.0009$ ($\pm 0.0027$) at the $1\sigma$ ($3\sigma$) level and we use leptonic unitarity triangles to illustrate the ability of global oscillation data to obtain information on CP violation. We discuss "tendencies and tensions" of the global fit related to the octant of $\theta_{23}$ as well as the CP violating phase $\delta_\mathrm{CP}$. The favored values of $\delta_\mathrm{CP}$ are around $3\pi/2$ while values around $\pi/2$ are disfavored at about $\Delta\chi^2 \simeq 6$. We comment on the non-trivial task to assign a confidence level to this $\Delta\chi^2$ value by performing a Monte Carlo study of T2K data.