Transition radiation by neutrinos

We calculate the transition radiation process ν→νγ at an interface of two media. The neutrinos are taken to be with only standard-model couplings. The medium fulfills the dual purpose of inducing an effective neutrino-photon vertex and of modifying the photon dispersion relation. The transition radiation occurs when at least one of those quantities have different values in different media. The neutrino mass is ignored due to its negligible contribution. We present a result for the probability of the transition radiation which is both accurate and analytic. For Eν=1 MeV neutrino crossing polyethylene-vacuum interface the transition radiation probability is about ¹⁰−39 and the energy intensity is about ¹⁰−34 eV. At the surface of the neutron stars the transition radiation probability may be ∼¹⁰−20. Our result is by the three orders of magnitude larger than those of previous calculations.