Search for Sterile Neutrinos at OPERA and other Long--Baseline Experiments

The OPERA experiment at the CNGS beam has observed muon to tau neutrino oscillations in the atmospheric sector. Based on this result new limits on the mixing parameters of a massive sterile neutrino may be set. Preliminary results of the analysis done in the 3+1 neutrino framework are here presented. An update of the search for sterile neutrinos in the ${\nu }_{\mu }\to {\nu }_e$ channel is also given. The status of the searches for sterile neutrinos performed at other Long–Baseline experiments (MINOS at NuMI beam and SuperK with the atmospheric flux) is also briefly recalled. Finally, some personal perspectives are discussed.