Low energy analysis of νN→νNγ in the standard model

The production of single photons in low energy (∼1 GeV) neutrino scattering off nucleons is analyzed in the standard model. At very low energies, Eν<<GeV, a simple description of the chiral Lagrangian involving baryons and arbitrary SU(2)LxU(1)Y gauge fields is developed. Extrapolation of the process into the ∼1-2 GeV region is treated in a simple phenomenological model. Coherent enhancements in compound nuclei are studied. The relevance of single-photon events as a background to experimental searches for νμ→νe is discussed. In particular, single photons are a plausible explanation for excess events observed by the MiniBooNE experiment.