A complete update of ${\epsilon }^{\mathrm{\prime }}\mathrm{/}\epsilon$ in the Standard Model

The recent release of improved lattice data has revived again the interest on precise theoretical calculations of the direct CP-violation ratio ${\epsilon }^{\mathrm{\prime }}\mathrm{/}\epsilon$. We present a complete update of the Standard Model prediction [1,2], including a new re-analysis of isospin-breaking corrections which are of vital importance in the theoretical determination of this observable. The Standard Model prediction, $$\mathrm{R}\mathrm{e}$ (\epsilon’/\epsilon) = (14\pm 5)\cdot 10^{-4}$, turns out to be in good agreement with the experimental measurement.