Paper detail

New limits on radiative sterile neutrino decays from a search for single photons in neutrino interactions

It has been recently shown that excess events observed by the LSND and MiniBooNE neutrino experiments could be interpreted as a signal from the radiative decay of a heavy sterile neutrino ν_h produced in ν_μneutral current-like interactions. If the ν_h exist, it would be also produced by the ν_μbeam from the CERN SPS in the neutrino beam line shielding. The ν_h's would penetrate the shielding and be observed through the decay ν_h -> νγ, followed by the photon conversion into e+e- pair in the active target of the NOMAD detector. The ν_h's could be also produced in the iron of the magnetic spectrometer of the CHORUS detector, located just in front of NOMAD. Considering these two sources of ν_h's we set new constraints on ν_h properties and exclude part of the LSND/MiniBooNE ν_h parameter space using bounds on single photons production in neutrino reactions recently reported by the NOMAD collaboration. We find that broad bands in the parameter space are still open for more sensitive searches for the ν_h in future neutrino experiments.