Neutrino masses and mixings: Status of known and unknown 3 Parameters
F. Capozzi (Dipartimento di Fisica e Astronomia “Galileo Galilei”, Università di Padova, Via F. Marzolo 8, Padova, Italy, Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Padova, Via F. Marzolo 8, Padova, Italy)
; E. Lisi (Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, Via E. Orabona 4, Bari, Italy); A. Marrone (Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, Via E. Orabona 4, Bari, Italy, Dipartimento Interateneo di Fisica “Michelangelo Merlin”, Università di Bari, Via G. Amendola 173, Bari, Italy); D. Montanino (Dipartimento di Matematica e Fisica “Ennio de Giorgi”, Università del Salento, Via Arnesano, Lecce, Italy, Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Lecce, Via Arnesano, Lecce, Italy); A. Palazzo (Istituto Nazionale di Fisica Nucleare (INFN), Sezione di Bari, Via E. Orabona 4, Bari, Italy, Dipartimento Interateneo di Fisica “Michelangelo Merlin”, Università di Bari, Via G. Amendola 173, Bari, Italy)
Within the standard 3ν 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 and ν 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 (, , , , ), and the status of the three remaining unknown parameters: the mass hierarchy [], the octant [], and the possible CP-violating phase δ. With respect to previous global fits, we find that the reanalysis of KamLAND data induces a slight decrease of both and , while the latest accelerator and atmospheric data induce a slight increase of . Concerning the unknown parameters, we confirm the previous intriguing preference for negative values of (with best-fit values around ), but we find no statistically significant indication about the octant or the mass hierarchy (normal or inverted). Assuming an alternative (so-called LEM) analysis of data, some δ ranges can be excluded at , and the normal mass hierarchy appears to be slightly favored at 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 ν mass scale: the sum of ν masses Σ (in cosmology), the effective mass (in beta decay), and the effective Majorana mass (in neutrinoless double beta decay).