$\Delta I =1/2$ process of $K\to\pi\pi$ decay on multiple ensembles with periodic boundary conditions

Abstract

We present our preliminary results for the $\Delta I = 1/2$ matrix elements of $K\to\pi\pi$ decay and $\varepsilon'$, the measure of direct $CP$ violation in $K\to\pi\pi$, computed on multiple ensembles with periodic boundary conditions (PBC) at the inverse lattice spacings of $a^{-1} \approx 1.0$~GeV and 1.4~GeV. The finer lattice ensemble is newly introduced as an extension to the first PBC calculation [1], while the calculation on the coarser ensemble is updated with the approximately doubled statistics. Our first attempt to take the continuum limit is also discussed with acknowledging potential significance of the $O(a^2)$ scaling violation on these coarse lattices.