Neutrino masses and mixings: Status of known and unknown 3ν parameters

2016/01/28 by Francesco Capozzi, F. Capozzi, E. Lisi +3 · 20 citations
Physics and Astronomy · #Astrophysics and Cosmic Phenomena #Neutrino Physics Research #Particle physics theoretical and experimental studies #hep-ph

paper · pdf · doi:10.1016/j.nuclphysb.2016.02.016

15 pages, 9 figures, 2 tables. Invited contribution prepared for the Nuclear Physics B Special Issue on "Neutrino Oscillations" celebrating the Nobel Prize in Physics 2015

arxiv created 2016/01/28 · openalex publication_date 2016/02/23 · arxiv updated 2016/06/22 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/31

Abstract

Within the standard 3nu mass-mixing framework, we present an up-to-date global analysis of neutrino oscillation data (as of January 2016), including the latest available results from experiments with atmospheric neutrinos (Super-Kamiokande and IceCube DeepCore), at accelerators (first T2K anti-nu and NOvA nu runs in both appearance and disappearance mode), and at short-baseline reactors (Daya Bay and RENO far/near spectral ratios), as well as a reanalysis of older KamLAND data in the light of the "bump" feature recently observed in reactor spectra. We discuss improved constraints on the five known oscillation parameters (delta m², |Delta m²|, sin²theta₁2, sin²theta₁3, sin²theta₂3), and the status of the three remaining unknown parameters: the mass hierarchy, the theta₂3 octant, and the possible CP-violating phase delta. With respect to previous global fits, we find that the reanalysis of KamLAND data induces a slight decrease of both delta m² and sin²theta₁2, while the latest accelerator and atmospheric data induce a slight increase of |Delta m²|. Concerning the unknown parameters, we confirm the previous intriguing preference for negative values of sin(delta) [with best-fit values around sin(delta) ~ -0.9], but we find no statistically significant indication about the theta₂3 octant or the mass hierarchy (normal or inverted). Assuming an alternative (so-called LEM) analysis of NOvA data, some delta ranges can be excluded at >3 sigma, and the normal mass hierarchy appears to be slightly favored at 90% C.L. We also describe in detail the covariances of selected pairs of oscillation parameters. Finally, we briefly discuss the implications of the above results on the three non-oscillation observables sensitive to the (unknown) absolute nu mass scale: the sum of nu masses, the effective nu_e mass, and the effective Majorana mass.

Citations

• Simulation of long-baseline neutrino oscillation experiments with GLoBES
• Tests of three-flavor mixing in long-baseline neutrino oscillation experiments
• New features in the simulation of neutrino oscillation experiments with GLoBES 3.0
• Improved predictions of reactor antineutrino spectra
• Reactor on-off antineutrino measurement with KamLAND
• On atmospheric neutrino mass-squared difference in the precision era
• Big-Bang Nucleosynthesis

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