Thomas Schwetz

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.

Sterile neutrino oscillations: the global picture

A bstractNeutrino oscillations involving eV-scale neutrino mass states are investigated in the context of global neutrino oscillation data including short and long-baseline accelerator, reactor, and radioactive source experiments, as well as atmospheric and solar neutrinos. We consider sterile neutrino mass schemes involving one or two mass-squared differences at the eV2 scale denoted by 3+1, 3+2, and 1+3+1. We discuss the hints for eV-scale neutrinos from

Series expansions for three flavor neutrino oscillation probabilities in matter

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Physics at a future Neutrino Factory and super-beam facility

disappearance (reactor and Gallium anomalies) and

Are There Sterile Neutrinos at the eV Scale

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Global neutrino data and recent reactor fluxes: status of three-flavour oscillation parameters

appearance (LSND and MiniBooNE) searches, and we present constraints on sterile neutrino mixing from

Large underground, liquid based detectors for astro-particle physics in Europe: Scientific case and prospects

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Sterile neutrino oscillations after first MiniBooNE results

and neutral-current disappearance data. An explanation of all hints in terms of oscillations suffers from severe tension between appearance and disappearance data. The best compatibility is obtained in the 1+3+1 scheme with a p-value of 0.2% and exceedingly worse compatibilities in the 3+1 and 3+2 schemes.