Updated global 3+1 analysis of short-baseline neutrino oscillations

A bstract 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 and ν ¯ e disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactor ν ¯ e spectrum in the NEOS experiment, which shifts the allowed regions of the parameter space towards smaller values of | U e 4 | 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 3 σ 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 and ν ¯ e disappearance as a function of distance. We then consider the global fit of the data on short-baseline ν μ − → ν e − transitions in the light of the LSND anomaly, taking into account the constraints from ν e − and ν μ − disappearance experiments, including the recent data of the MINOS and IceCube experiments. The combination of the NEOS constraints on | U e 4 | 2 and the MINOS and IceCube constraints on | U μ 4 | 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 Δ m 41 2 , | U e 4 | 2 , | U μ 4 | 2 , and | U τ 4 | 2 leads to three allowed regions with narrow Δ m 41 2 widths at Δ m 41 2 ≈ 1.7 (best-fit), 1.3 (at 2 σ ), 2.4 (at 3 σ ) eV 2 . The effective amplitude of short-baseline ν μ − → ν e − oscillations is limited by 0.00048 ≲ sin 2 2 ϑ eμ ≲ 0.0020 at 3 σ . 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.