Estimates of $ϵ\prime /ϵ$

Abstract

We review the latest calculations of the next-to-leading $\text{DSone}$ effective Hamiltonian, relevant for $K\to \pi \pi$ transitions. Numerical results for the Wilson coefficients are given for different regularization schemes. Predictions of $\text{epse}$, obtained using different approaches to evaluate the relevant hadronic matrix elements, are compared. Given the present value of the top mass, $m_t=(174\pm 17)$ GeV, all the analyses, in spite of the large theoretical uncertainties, indicate that the value of $\text{epse}$ is smaller than $1\times 10^{-3}$.

Comments: LaTeX, 29 pages, 5 postscript figures, contribution to the 2nd Daphne Physics Handbook