Sterile neutrino oscillations after first MiniBooNE results

In view of the recent results from the MiniBooNE experiment we revisit the global neutrino oscillation fit to short-baseline neutrino data by adding one or two sterile neutrinos with eV-scale masses to the three Standard Model neutrinos, and for the first time we consider also the global fit with three sterile neutrinos. Four-neutrino oscillations of the (3+1) type have been only marginally allowed before the recent MiniBooNE results, and become even more disfavored with the new data. In the framework of so-called (3+2) five-neutrino mass schemes the MiniBooNE results are in perfect agreement with the LSND appearance evidence thanks to the possibility of CP violation available in such oscillation schemes. Furthermore, (3+2) oscillations provide an excellent fit to the full MiniBooNE spectrum, including the event excess at low energies. However, the tension between appearance and disappearance experiments represents a problem in (3+2) schemes. This tension remains also when a third sterile neutrino is added, and we do not find a significant improvement of the global fit in a (3+3) scheme.