M. C. Gonzalez-Garcia

Global fit to three neutrino mixing: critical look at present precision

A bstractWe present an up-to-date global analysis of solar, atmospheric, reactor, and accelerator neutrino data in the framework of three-neutrino oscillations. We provide results on the determination of θ13 from global data and discuss the dependence on the choice of reactor fluxes. We study in detail the statistical significance of a possible deviation of θ23 from maximal mixing, the determination of its octant, the ordering of the mass states, and the sensitivity to the CP violating phase, and discuss the role of various complementary data sets in those respects.

Updated fit to three neutrino mixing: status of leptonic CP violation

A bstractWe present a global analysis of solar, atmospheric, reactor and accelerator neutrino data in the framework of three-neutrino oscillations based on data available in summer 2014. We provide the allowed ranges of the six oscillation parameters and show that their determination is stable with respect to uncertainties related to reactor neutrino and solar neutrino flux predictions. We find that the maximal possible value of the Jarlskog invariant in the lepton sector is 0.033 ±0.010 (±0.027) at the 1σ (3σ) level and we use leptonic unitarity triangles to illustrate the ability of global oscillation data to obtain information on CP violation. We discuss “tendencies and tensions” of the global fit related to the octant of θ23 as well as the CP violating phase δCP. The favored values of δCP are around 3π/2 while values around π/2 are disfavored at about Δχ2 ≃6. We comment on the non-trivial task to assign a confidence level to this Δχ2 value by performing a Monte Carlo study of T2K data.

Updated fit to three neutrino mixing: exploring the accelerator-reactor complementarity

A bstractWe perform a combined fit to global neutrino oscillation data available as of fall 2016 in the scenario of three-neutrino oscillations and present updated allowed ranges of the six oscillation parameters. We discuss the differences arising between the consistent combination of the data samples from accelerator and reactor experiments compared to partial combinations. We quantify the confidence in the determination of the less precisely known parameters θ23, δCP, and the neutrino mass ordering by performing a Monte Carlo study of the long baseline accelerator and reactor data. We find that the sensitivity to the mass ordering and the θ23 octant is below 1σ. Maximal θ23 mixing is allowed at slightly more than 90% CL. The best fit for the CP violating phase is around 270°, CP conservation is allowed at slightly above 1σ, and values of δCP ≃ 90° are disfavored at around 99% CL for normal ordering and higher CL for inverted ordering.

Updated global fit to three neutrino mixing: status of the hints of θ13 > 0

We present an up-to-date global analysis of solar, atmospheric, reactor and accelerator neutrino data in the framework of three-neutrino oscillations. We discuss in detail the statistical significance of the observed “hint” of non-zero θ13 in the solar sector at the light of the latest experimental advances, such as the Borexino spectral data, the lower value of Gallium rate recently measured in SAGE, and the low energy threshold analysis of the combined SNO phase I and phase II. We also study the robustness of the results under changes of the inputs such as the choice of solar model fluxes and a possible modification of the Gallium capture cross-section as proposed by SAGE. In the atmospheric sector we focus on the latest results for νe appearance from MINOS and on the recent Super-Kamiokande results from the combined phases I, II and III, and we discuss their impact on the determination of θ13. Finally, we combine all the data into a global analysis and determine the presently allowed ranges of masses and mixing.

Global analyses of neutrino oscillation experiments

We summarize the determination of some neutrino properties from the global analysis of solar, atmospheric, reactor, and accelerator neutrino data in the framework of three-neutrino mixing as well as in some extended scenarios such as the mixing with eV-scale sterile neutrinos invoked for the interpretation of the short baseline anomalies, and the presence of non-standard neutrino interactions.

Solar neutrinos before and after Neutrino 2004

We compare, using a three neutrino analysis, the allowed neutrino oscillation parameters and solar neutrino fluxes determined by the experimental data available Before and After Neutrino 2004. New data available after Neutrino 2004 include refined KamLAND and gallium measurements. We use six different approaches to analyzing the KamLAND data. We present detailed results using all the available neutrino and anti-neutrino data for ?m221, tan 2?12, sin 2?13, and sin 2? (sterile fraction). Using the same complete data sets, we also present Before and After determinations of all the solar neutrino fluxes (which are treated as free parameters), an upper limit to the luminosity fraction associated with CNO neutrinos, and the predicted rate for a 7Be solar neutrino experiment. The 1? (3?) allowed range of ?m221 = 8.2+0.3?0.3(+1.0?0.8) ? 10?5?eV2 is decreased by a factor of 1.7 (5), but the allowed ranges of all other neutrino oscillation parameters and neutrino fluxes are not significantly changed. Maximal ?12 mixing is disfavored at 5.8? and the bound on the mixing angle ?13 is slightly improved to sin 2?13<0.048 at 3?. The predicted rate in a 7Be neutrino-electron scattering experiment is 0.665?0.015?(+0.045?0.040) of the rate implied by the BP04 solar model in the absence of neutrino oscillations. The corresponding predictions for p?p and pep experiments are, respectively, 0.707+0.011?0.013(+0.041?0.039) and 0.644+0.011?0.013(+0.045?0.037). In order to clarify what measurements constrain which parameters best, we also analyze the solar neutrino data separately and the reactor anti-neutrino data separately, both Before and After Neutrino 2004. We derive upper limits to CPT violation in the weak sector by comparing reactor anti-neutrino oscillation parameters with neutrino oscillation parameters. We also show that the recent data disfavor at 91% CL a proposed non-standard interaction description of solar neutrino oscillations. We have verified that our results are insensitive (changes much less than 1?) to which of six approaches we use in analyzing the KamLAND data, which of the published 8B neutrino energy spectra we adopt, and the precise value of the gallium solar neutrino event rate.

Robust cosmological bounds on neutrinos and their combination with oscillation results

We perform a global analysis of cosmological observables in generalized cosmologies which depart from ΛCDM models by allowing non-vanishing curvature Ωk 6= 0, dark energy with equation of state with ω ≠ −1, the presence of additional relativistic degrees of freedom ΔNrel, and neutrino masses Ων= 0. By combining the data from cosmic microwave background (CMB) experiments (in particular the latest results from WMAP-7), the present day Hubble constant (H0) measurement, the high-redshift Type-I supernovae (SN) results and the information from large scale structure (LSS) surveys, we determine the parameters in the 10-dimensional parameter space for such models. We present the results from the analysis when the full shape information from the LSS matter power spectrum (LSSPS) is included versus when only the corresponding distance measurement from the baryon acoustic oscillations (BAO) is accounted for. We compare the bounds on the neutrino mass scale in these generalized scenarios with those obtained for the 6+1 parameter analysis in ΛCDM + mν models and we also study the dependence of those on the set of observables included in the analysis. Finally we combine these results with the information on neutrino mass differences and mixing from the global analysis of neutrino oscillation experiments and derive the presently allowed ranges for the two laboratory probes of the absolute scale of neutrino mass: the effective electron neutrino mass in single beta decay and the effective Majorana neutrino mass in neutrinoless ββ decay.

Three-neutrino mixing after the first results from K2K and KamLAND

We analyze the impact of the data on long-baseline n m disappearance from the K2K experiment and reactor n e disappearance from the KamLAND experiment on the determination of the leptonic three-generation mixing parameters. Performing an up-to-date global analysis of solar, atmospheric, reactor, and long-baseline neutrino data in the context of three-neutrino oscillations, we determine the presently allowed ranges of masses and mixing and we consistently derive the allowed magnitude of the elements of the leptonic mixing matrix. We also quantify the maximum allowed contribution of Dm21 oscillations to CP-odd and CP-even observables at

Determination of matter potential from global analysis of neutrino oscillation data

A bstractWe quantify our current knowledge of the size and flavor structure of the matter effects in the evolution of neutrinos based solely on the global analysis of oscillation neutrino data. The results are translated in terms of the present allowed ranges for the corresponding non-standard neutrino interactions in matter.

Bayesian global analysis of neutrino oscillation data

A bstractWe perform a Bayesian analysis of current neutrino oscillation data. When estimating the oscillation parameters we find that the results generally agree with those of the χ2 method, with some differences involving s232 and CP-violating effects. We discuss the additional subtleties caused by the circular nature of the CP-violating phase, and how it is possible to obtain correlation coefficients with s232. When performing model comparison, we find that there is no significant evidence for any mass ordering, any octant of s232 or a deviation from maximal mixing, nor the presence of CP-violation.