3+1 and 3+2 sterile neutrino fits

We present the results of fits of short-baseline neutrino-oscillation data in 3 + 1 and 3 + 2 neutrino-mixing schemes. In spite of the presence of a tension in the interpretation of the data, 3 + 1 neutrino mixing is attractive for its simplicity and for the natural correspondence of one new entity (a sterile neutrino) with a new effect (short-baseline oscillations). The allowed regions in the oscillation parameter space can be tested in near-future experiments. In the framework of 3 + 2 neutrino mixing, there is less tension in the interpretation of the data, at the price of introducing a second sterile neutrino. Moreover, the improvement of the parameter goodness of fit is mainly a statistical effect due to an increase in the number of parameters. The CP violation in short-baseline experiments allowed in 3 + 2 neutrino mixing can explain the positive <(nu)(mu)over bar> -> (nu) over bar (e) signal and the negative <(nu)(mu)over bar> -> (nu) over bar (e) measurement in the MiniBooNE experiment. For the CP-violating phase, we obtained two minima of the marginal chi(2) close to the two values where CP violation is maximal.