CPNonconservation at theZ0Peak

Abstract

The measurement of a nonvanishing asymmetry $\alpha \equiv \frac{\left[\Gamma \right(s\overline{b})-\Gamma (\overline{s}b\left)\right]}{\left[\Gamma \right(s\overline{b})+\Gamma (\overline{s}b\left)\right]}$ would signal $\mathrm{CP}$ nonconservation in $Z^0$ decays. We study here this effect within the standard model. In the three-generation case, the $\alpha$ value comes out small because of the effective degeneracy of $u$ and $c$ quarks at these high energies. In the four-generation case, results are encouraging for the CERN $e^{+}{e}^{-}$ collider LEP: One could have a branching ratio of this flavor-changing decay to the flavor-conserving one of ∼${10}^{-6\mathrm{}}$ and reach $\alpha$ values near unity.