Phenomenological Description of an Unstable Fermion

Abstract

We present a phenomenological description for an unstable fermion based upon one-loop renormalization of quantum field theory. It is emphasized that wave function renormalization can introduce important $CP$-conserving and $CP$-violating phases. Implications for the study of $CP$ violation are examined. Applications are given to $CP$-violating asymmetries in the $t$ decays: $t\to b{W}^{+},b{H}^{+}$, in which we show that a naive calculation following the standard rule either is incomplete or violates $CPT$.

Comments: 20 pages, one Feynman diagram (not included), UPR-0558T