Global analysis of three-flavour neutrino oscillations: synergies and tensions in the determination of θ23, δCP, and the mass ordering

TLDR

The study performs a global analysis of neutrino oscillation data up to fall 2018 to determine the allowed ranges of the six neutrino oscillation parameters. The analysis combines diverse data sets, quantifies tensions among them, and incorporates the Super‑Kamiokande atmospheric neutrino χ² map to refine the parameter determinations. The best fit favors normal mass ordering (Δχ² = 4.7–9.3 with SK‑atm), the second octant of θ₂₃ (Δχ² = 4.4–6.0), and a CP‑violating phase δCP ≈ 215°, with CP conservation allowed at Δχ² ≈ 1.5–1.8.

Abstract

A bstract We present the results of a global analysis of the neutrino oscillation data available as of fall 2018 in the framework of three massive mixed neutrinos with the goal at determining the ranges of allowed values for the six relevant parameters. We describe the complementarity and quantify the tensions among the results of the different data samples contributing to the determination of each parameter. We also show how those vary when combining our global likelihood with the χ 2 map provided by Super-Kamiokande for their atmospheric neutrino data analysis in the same framework. The best fit of the analysis is for the normal mass ordering with inverted ordering being disfavoured with a Δ χ 2 = 4.7 (9.3) without (with) SK-atm. We find a preference for the second octant of θ 23 , disfavouring the first octant with Δ χ 2 = 4.4 (6.0) without (with) SK-atm. The best fit for the complex phase is δ CP = 215° with CP conservation being allowed at Δ χ 2 = 1.5 (1.8). As a byproduct we quantify the correlated ranges for the laboratory observables sensitive to the absolute neutrino mass scale in beta decay, $$ {m}_{\nu_e} $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>m</mml:mi> <mml:msub> <mml:mi>ν</mml:mi> <mml:mi>e</mml:mi> </mml:msub> </mml:msub> </mml:math> , and neutrino-less double beta decay, m ee , and the total mass of the neutrinos, Σ, which is most relevant in Cosmology.