Sterile neutrinos at the CNGS

We study the potential of the CNGS beam in constraining the parameter space of a model with one sterile neutrino separated from three active ones by an O(eV(2)) mass-squared difference, Delta m(SBL)(2). We perform our analysis using the OPERA detector as a reference (our analysis can be upgraded including a detailed simulation of the ICARUS detector). We point out that the channel with the largest potential to constrain the sterile neutrino parameter space at the CNGS beam is nu(mu) --> nu(tau). The reason for that is twofold: first, the active-sterile mixing angle that governs this oscillation is the less constrained by present experiments; second, this is the signal for which both OPERA and ICARUS have been designed, and thus benefits from an extremely low background. In our analysis we also took into account nu(mu) --> nu(e) oscillations. We find that the CNGS potential to look for sterile neutrinos is limited with nominal intensity of the beam, but it is significantly enhanced with a factor 2 to 10 increase in the neutrino flux. Data from both channels allow us, in this case, to constrain further the four-neutrino model parameter space. Our results hold for any value of Delta m(SBL)(2) greater than or similar to 0.1 eV(2), i.e. when oscillations driven by this mass-squared difference are averaged. We have also checked that the bound on theta 13 that can be put at the CNGS is not affected by the possible existence of sterile neutrinos.