CPNonconservation in Decays ofWandZBosons

Abstract

The possibility of $\mathrm{CP}$ asymmetries in decays of $W$ and $Z$ bosons is examined. The asymmetries studied are the differences in the branching ratios of charge-conjugate modes such as $W^{+}\to t\overline{b}$ vs $W^{-}\to \overline{t}b$ or $Z\to \overline{b}s$ vs $Z\to b\overline{s}$ In the standard model, with three generations, such effects are found to be vanishingly small. With four generations, flavor-changing transitions such as $Z\to b\overline{s}$ or $b^{\prime }\overline{b}$ may be observable, but the prospects for observing $\mathrm{CP}$ asymmetries appear discouraging. We also discuss the situation in some other models of $\mathrm{CP}$ nonconservation.