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

Within the standard 3 nu 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 (nu) over bar and NO nu A nu runs in both appearance and disappearance modes), 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 m(2), vertical bar Delta m(2)vertical bar, sin(2)theta(12), sin(2)theta(13), sin(2)theta(23)), and the status of the three remaining unknown parameters: the mass hierarchy [sign(+/-Delta m(2))], the theta(23) octant [sign(sin(2)theta(23)-1/2)], 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 m(2) and sin(2)theta(12), while the latest accelerator and atmospheric data induce a slight increase of vertical bar Delta m(2)vertical bar. Concerning the unknown parameters, we confirm the previous intriguing preference for negative values of sin delta (with best-fit values around sin delta similar or equal to -0.9), but we find no statistically significant indication about the theta(23) octant or the mass hierarchy (normal or inverted). Assuming an alternative (so-called LEM) analysis of NO nu Adata, some delta ranges can be excluded at >3 sigma, and the normal mass hierarchy appears to be slightly favored at similar to 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 Sigma (in cosmology), the effective nu(e) mass m(beta) (in beta decay), and the effective Majorana mass m(beta beta) (in neutrinoless double beta decay). (C) 2016 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP(3).