A 1996 Analysis of the CP Violating Ratio epsilon'/epsilon

Abstract

We update our 1993 analysis of the CP violating ratio $\epe$ in view of the changes in several input parameters, in particular the improved value of the top quark mass. We also investigate the strange quark mass $m_s$ dependence of $\epe$ in view of rather low values found in the most recent lattice calculations. A simple scanning of the input parameters within one standard deviation gives the ranges: $-1.2 \cdot 10^{-4} \le \epe \le 16.0 \cdot 10^{-4}$ and $0 \le \epe \le 43.0 \cdot 10^{-4}$ for $\ms(\mc)=150\pm20~ \mev$ and $\ms(\mc)=100\pm20~ \mev$ respectively. If the experimentally measured numbers and the theoretical input parameters are used with Gaussian errors, we find $\epe= ( 3.6\pm 3.4) \cdot 10^{-4}$ and $\epe= ( 10.4\pm 8.3) \cdot 10^{-4}$ respectively. We also give results for ${\rm Im} V_{ts}^*V_{td}$. Analyzing the dependence of $\epe$ on various parameters we find that only for $\ms(\mc)\le 100\,\mev$ and a conspiration of other input parameters, values for $\epe$ as large as $(2-4) \cdot 10^{-3}$ and consistent with the NA31 result can be obtained.