Abstract

Neutrino oscillations are a well established phenomena, which can be very well explained within the standard framework of three flavour neutrino oscillations. However, some short-baseline experiments present anomalies in both electron neutrino disappearance and electron neutrino appearance.

In the electron neutrino disappearance channel, the Reactor anti-neutrino and Gallium anomalies, which consist of a deficit of measured neutrino events with respect to the predictions, can be explained introducing sterile neutrino oscillations within a 3+1 framework. A global analysis of the electron neutrino disappearance data, up to summer 2018, is in favor of sterile neutrino oscillations at the 3 \sigma level with \Delta m_{41}^{2_{1.3 eV}}2 and |U_{e4}|0.1.

On the other hand, the electron neutrino appearance anomaly, mainly driven by the MiniBooNE excess, is in strong tension, at the 4.7 \sigma level, with the limits coming from the muon neutrino disappearance data. The fact that this tension is independent of any muon neutrino appearance data set and of the reactor antineutrino anomaly, rule out the MiniBooNE excess explanation in terms of sterile neutrino oscillations. An alternative and possible solution to the MiniBooNE low energy excess, based on a heavy neutrino decay, will be also presented.