Large ν μ → ν τ and ν e → ν τ transitions in short - baseline experiments ?

Considering four-neutrino schemes of type 3+1, we identify four small regions of the neutrino mixing parameter space compatible with all data. Assuming a small mixing between the sterile neutrino and the isolated mass eigenstate we show that large νμ → ντ and νe → ντ transitions are predicted in short-baseline experiments and could be observed in the near future in dedicated experiments. We discuss also implications for solar, atmospheric and long-baseline neutrino experiments and we present a formalism that allows to describe in 3+1 schemes atmospheric neutrino oscillations, long-baseline νμ disappearance and νμ → ντ transitions in matter. PACS numbers: 14.60.St Typeset using REVTEX 1