A new probe of lepton flavour violation

We study lepton flavour violation via flavour changing Rutherford scattering, i.e. the conversion of relativistic electrons into muons by scattering in the external field of a massive nucleus. We show that for a class of models with heavy neutrinos and extended gauge sectors, all the unknown form-factors associated with purely electromagnetic transitions may be absorbed into the predicted value of Γμ→eγ, leading to a compact analytical expression for the cross-section. The experimental realisation via a beam-dump experiment at LEP is discussed.