A. Marrone

Global analysis of three-flavor neutrino masses and mixings

We present a comprehensive phenomenological analysis of a vast amount of data from neutrino flavor oscillation and non-oscillation searches, performed within the standard scenario with three massive and mixed neutrinos, and with particular attention to subleading effects. The detailed results discussed in this review represent a state-of-the-art, accurate and up-to-date (as of August 2005) estimate of the three-neutrino mass-mixing parameters.

Hints of

Nailing down the unknown neutrino mixing angle theta{13} is one of the most important goals in current lepton physics. In this context, we perform a global analysis of neutrino oscillation data, focusing on theta{13}, and including recent results [ (unpublished)]. We discuss two converging hints of theta{13}>0, each at the level of approximately 1sigma: an older one coming from atmospheric neutrino data, and a newer one coming from the combination of solar and long-baseline reactor neutrino data. Their combination provides the global estimate sin{2}theta{13}=0.016+/-0.010(1sigma), implying a preference for theta{13}>0 with non-negligible statistical significance ( approximately 90% C.L.). We discuss possible refinements of the experimental data analyses, which might sharpen such intriguing indications.

\theta_{13}

In this followup to Phys. Rev. D 75, 053001 (2007) , we report updated constraints on neutrino mass-mixing parameters, in light of recent neutrino oscillation data (KamLAND, SNO, and MINOS) and cosmological observations (WMAP 5-year and other data). We discuss their interplay with the final 0{nu}2{beta} decay results in {sup 76}Ge claimed by part of the Heidelberg-Moscow Collaboration, using recent evaluations of the corresponding nuclear matrix elements, and their uncertainties. We also comment on the 0{nu}2{beta} limits in {sup 130}Te recently set by Cuoricino and on prospective limits or signals from the Karlsruhe tritium neutrino experiment.

> 0 from global neutrino data analysis

Abstract 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 ν ‾ and NO ν A 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 ( δ m 2 , | Δ m 2 | , sin 2 u2061 θ 12 , sin 2 u2061 θ 13 , sin 2 u2061 θ 23 ), and the status of the three remaining unknown parameters: the mass hierarchy [ sign ( ± Δ m 2 ) ], the θ 23 octant [ sign ( sin 2 u2061 θ 23 − 1 / 2 ) ], 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 δ m 2 and sin 2 u2061 θ 12 , while the latest accelerator and atmospheric data induce a slight increase of | Δ m 2 | . Concerning the unknown parameters, we confirm the previous intriguing preference for negative values of sin u2061 δ (with best-fit values around sin u2061 δ ≃ − 0.9 ), but we find no statistically significant indication about the θ 23 octant or the mass hierarchy (normal or inverted). Assuming an alternative (so-called LEM) analysis of NO ν A data, some δ ranges can be excluded at > 3 σ , 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 ν mass scale: the sum of ν masses Σ (in cosmology), the effective ν e mass m β (in beta decay), and the effective Majorana mass m β β (in neutrinoless double beta decay).

Observables sensitive to absolute neutrino masses. II

It is shown that the results of the Super-Kamiokande atmospheric neutrino experiment, interpreted in terms of nu(mu)<-->nu(tau) flavor transitions, can probe possible decoherence effects induced by new physics (e.g., by quantum gravity) with high sensitivity, supplementing current laboratory tests based on kaon oscillations and on neutron interferometry. By varying the (unknown) energy dependence of such effects, one can either obtain strong limits on their amplitude or use them to find an unconventional solution to the atmospheric nu anomaly based solely on decoherence.

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

We analyze the magnitude-redshift data of type Ia supernovae included in the Union and Union2 compilations in the framework of an anisotropic Bianchi type I cosmological model and in the presence of a dark energy fluid with anisotropic equation of state. We find that the amount of deviation from isotropy of the equation of state of dark energy, the skewness �, and the present level of anisotropy of the large-scale geometry of the Universe, the actual shear �0, are constrained in the ranges −0.16 . � . 0.12 and −0.012 . �0 . 0.012 (1� C.L.) by Union2 data. Supernova data are then compatible with a standard isotropic universe (� = �0 = 0), but a large level of anisotropy, both in the geometry of the Universe and in the equation of state of dark energy, is allowed.

Probing Possible Decoherence Effects in Atmospheric Neutrino Oscillations

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).

Testing the Isotropy of the Universe with Type Ia Supernovae

We discuss the results of an updated global analysis of neutrino oscillation data, focusing on the determination of θ13, the smallest and unknown leptonic mixing angle. We discuss three independent and converging hints of θ13 > 0: a first one coming from atmospheric neutrino data; a second one from the combination of solar and long-baseline reactor (KamLAND) neutrino data; and a third one from the latest MINOS measurements in the appearance (νμ → νe) channel. Their combination provides an indication for θ13 > 0 at the 2σ (95% C.L.) level.

Current unknowns in the three-neutrino framework

Abstract The recent observations of atmospheric ν events from the Super-Kamiokande experiment are compatible with two-flavor oscillations in the ν μ ↔ ν τ channel (“standard” interpretation). Among the possible deviations from this standard picture, we investigate two cases: (1) three-flavor oscillations and (2) a specific solution without oscillations (namely, neutrino decay). While the first solution appears perfectly viable, provided that the 3 ν oscillations occur dominantly in the ν μ ↔ ν τ channel and subdominantly in the ν μ ↔ ν e channel, the second is shown to be incompatible with the data. The derivation of such results is based on an updated analysis, including the latest 45 kTy data sample from Super-Kamiokande. A comparison with our previous results, based on 33 kTy data, shows that the oscillation evidence is strengthened, and that the neutrino mass-mixing parameters are constrained in smaller ranges.

Probing θ13 with global neutrino data analysis

We discuss the present knowledge of the neutrino oscillation parameters, the two mass squared differences (δm 2, Δm 2), the three mixing angles (θ 12, θ 13, θ 23) and one phase δ. While five out of these six parameters have been measured, the CP-violating phase δ remains unknown. Moreover, the octant of the mixing angle θ 23 and the neutrino mass ordering are still undetermined. We update our previous analysis, by adding to the global fit the recent results presented at The XXVII International Conference on Neutrino Physics and Astrophysics (Neutrino 2016) by the experiments T2K, NOνA, Super-Kamiokande, Daya Bay and RENO.