Anomalous Decay of Heavy Fermions by Electroweak Instanton

Abstract

The presence of a heavy fermion doublet in the electroweak instanton probably leads to unsuppressed fermion number nonconservation. By calculating numerically the effective potential barrier of electroweak instanton with heavy fermion in Minkowski space by using semiclassical approximation, it is shown that, if the mass of heavy fermion exceeds a critical value [Formula: see text] TeV (for MH = MW), the tunneling by electroweak instanton should be unsuppressed and the heavy fermion decays with fermion number violation. The dependence of critical fermion mass on the Higgs mass is also presented.