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

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 ν̄ₑ disappearance in the light of the Gallium and reactor anomalies. We discuss the implications of the recent measurement of the reactor ν̄ₑ 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 and ν̄ₑ disappearance as a function of distance. We then consider the global fit of the data on short-baseline _νμ⁽⁻⁾→νₑ⁽⁻⁾ transitions in the light of the LSND anomaly, taking into account the constraints from νₑ⁽⁻⁾ and _νμ⁽⁻⁾ 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 Δm 41 2 , |U e4|2, |U μ4|2, and |U τ4|2 leads to three allowed regions with narrow Δm 41 2 widths at Δm 41 2 ≈ 1.7 (best-fit), 1.3 (at 2σ), 2.4 (at 3σ) eV2. The effective amplitude of short-baseline _νμ⁽⁻⁾→νₑ⁽⁻⁾ oscillations is limited by 0.00048 ≲ sin2 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.