No abstract

We calculate the statistical significance of the anomalous deficit of electron neutrinos measured in the radioactive source experiments of the GALLEX and SAGE solar neutrino detectors, taking into account the uncertainty of the detection cross section. We found that the statistical significance of the anomaly is similar to 3.0 sigma. A fit of the data in terms of neutrino oscillations favors at similar to 2.7 sigma short-baseline electron neutrino disappearance with respect to the null hypothesis of no oscillations

This review is focused on neutrino mixing and neutrino oscillations in the light of the recent experimental developments. After discussing possible types of neutrino mixing for Dirac and Majorana neutrinos and considering in detail the phenomenology of neutrino oscillations in vacuum and matter, we review all existing evidence and indications in favour of neutrino oscillations that have been obtained in the atmospheric, solar and LSND experiments. We present the results of the analyses of the neutrino oscillation data in the framework of mixing of three and four massive neutrinos and investigate possibilities to test the different neutrino mass and mixing schemes obtained in this way. We also discuss briefly future neutrino oscillation experiments.

We review the theory and phenomenology of neutrino electromagnetic interactions, which give us powerful tools to probe the physics beyond the Standard Model. After a derivation of the general structure of the electromagnetic interactions of Dirac and Majorana neutrinos in the one-photon approximation, we discuss the effects of neutrino electromagnetic interactions in terrestrial experiments and in astrophysical environments. We present the experimental bounds on neutrino electromagnetic properties and we confront them with the predictions of theories beyond the Standard Model.

We present the results of an updated fit of short-baseline neutrino oscillation data in the framework of 3+1 active-sterile neutrino mixing. We first consider ν e andν e disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactorν e spectrum in the NEOS experiment, which shifts the allowed regions of the parameter space towards smaller values of |U e4 | 2 . The β-decay constraints of the Mainz and Troitsk experiments allow us to limit the oscillation length between about 2 cm and 7 m at 3σ for neutrinos with an energy of 1 MeV. The corresponding oscillations can be discovered in a model-independent way in ongoing reactor and source experiments by measuring ν e andν e disappearance as a function of distance. We then consider the global fit of the data on short-baselinetransitions in the light of the LSND anomaly, taking into account the constraints from ν µ disappearance experiments, including the recent data of the MINOS and IceCube experiments. The combination of the NEOS constraints on |U e4 | 2 and the MINOS and IceCube constraints on |U µ4 | 2 lead to an unacceptable appearance-disappearance tension which becomes tolerable only in a pragmatic fit which neglects the MiniBooNE low-energy anomaly. The minimization of the global χ 2 in the space of the four mixing parameters Open Access, c The Authors. Article funded by SCOAP 3 .https://doi.org/10.1007/JHEP06 (2017)135 JHEP06 (2017)135 ∆m 2 41 , |U e4 | 2 , |U µ4 | 2 , and |U τ 4 | 2 leads to three allowed regions with narrow ∆m 2 41 widths at ∆m 2 41 ≈ 1.7 (best-fit), 1.3 (at 2σ), 2.4 (at 3σ) eV 2 . The effective amplitude of short-baselineν e oscillations is limited by 0.00048 sin 2 2ϑ eµ 0.0020 at 3σ. The restrictions of the allowed regions of the mixing parameters with respect to our previous global fits are mainly due to the NEOS constraints. We present a comparison of the allowed regions of the mixing parameters with the sensitivities of ongoing experiments, which show that it is likely that these experiments will determine in a definitive way if the reactor, Gallium and LSND anomalies are due to active-sterile neutrino oscillations or not.

Abstract. The theory and phenomenology of light sterile neutrinos at the eV mass scale is reviewed. The reactor, Gallium and LSND anomalies are briefly described and interpreted as indications of the existence of short-baseline oscillations which require the existence of light sterile neutrinos. The global fits of short-baseline oscillation data in 3+1 and 3+2 schemes are discussed, together with the implications for β-decay and neutrinoless double-β decay. The cosmological effects of light sterile neutrinos are briefly reviewed and the implications of existing cosmological data are discussed. The review concludes with a summary of future perspectives.

We present the results of global analyses of short-baseline neutrino oscillation data in 3+1, 3+2 and 3+1+1 neutrino mixing schemes. We show that the data do not allow us to abandon the simplest 3+1 scheme in favor of the more complex 3+2 and 3+1+1 schemes. We present the allowed region in the 3+1 parameter space, which is located at Δm412 between 0.82 and 2.19  eV2 at 3σ. The case of no oscillations is disfavored by about 6σ, which decreases dramatically to about 2σ if the Liquid Scintillating Neutrino Detector (LSND) data are not considered. Hence, new high-precision experiments are needed to check the LSND signal

No abstract