Current unknowns in the three neutrino framework

TL;DR

This paper provides a comprehensive analysis of current neutrino oscillation data, highlighting the favored mass ordering, constraints on CP violation, and unresolved parameters like the mixing angle octant and absolute masses.

Contribution

It offers an updated global fit of three-neutrino parameters, clarifying the status of known and unknown quantities in neutrino physics as of 2018.

Findings

Normal mass ordering is favored at 3sigma

CP phase is constrained near maximal violation

Octant and absolute masses remain undetermined

Abstract

We present an up-to-date global analysis of data coming from neutrino oscillation and non-oscillation experiments, as available in April 2018, within the standard framework including three massive and mixed neutrinos. We discuss in detail the status of the three-neutrino (3nu) mass-mixing parameters, both known and unknown. Concerning the latter, we find that: normal ordering (NO) is favored over inverted ordering (IO) at 3sigma level; the Dirac CP phase is constrained within ~15% (~9%) uncertainty in NO (IO) around nearly-maximal CP-violating values; the octant of the largest mixing angle and the absolute neutrino masses remain undetermined. We briefly comment on other unknowns related to theoretical and experimental uncertainties (within 3nu) or possible new states and interactions (beyond 3nu).