Current status of ${\epsilon }^{\prime }/\epsilon$ in the Standard Model

Abstract

A recent lattice prediction of ${\epsilon }^{\prime }/\epsilon$, with a 2.1 $\sigma$ deviation from the experimental value, has triggered several studies of possible contributions from physics beyond the Standard Model. We have recently updated the SM prediction, including all known short-distance and long-distance contributions, our result $\text{mbox}Re\left({\epsilon }^{\prime }/\epsilon \right)=(15\pm 7)\cdot 10^{-4}$ is in complete agreement with the experimental measurement. In addition, we emphasize on the importance of the long-distance re-scattering of the final pions in $K\to \pi \pi$ for a correct prediction of ${\epsilon }^{\prime }/\epsilon$.

Comments: 9 pages, 1 figure,XIII Quark Confinement and the Hadron Spectrum - Confinement2018, 31 July - 6 August 2018, Maynooth University, Ireland. arXiv admin note: substantial text overlap with arXiv:1810.04904