Strong Enhancement of $\epsilon'/\epsilon$ Through Final State Interactions

TL;DR

This paper demonstrates that including strong final state interactions in the analysis of $K o2\pi$ decays significantly enhances the theoretical prediction of $ ext{ extepsilon'} ext{/} extepsilon$, aligning it with experimental data.

Contribution

It quantifies the impact of final state interactions on $K o2\pi$ amplitudes, showing they substantially increase the Standard Model prediction of $ ext{ extepsilon'} ext{/} extepsilon$.

Findings

Final state interactions provide a strong enhancement of the $ ext{ extDelta} I=1/2$ amplitude.

Including these effects aligns theoretical predictions with experimental measurements.

Rescattering of pions significantly affects weak decay amplitudes.

Abstract

We quantify the important effect of strong final state interactions in the weak $K\to2\pi$ amplitudes, using the measured $\pi$--$\pi$ phase shifts with J=0 and $I=0,2$. The final rescattering of the two pions provides a strong enhancement of the $\Delta I =1/2$ amplitude, which so far has been neglected in the theoretical predictions of $\epsilon'/\epsilon$. This correction increases the Standard Model prediction of $\epsilon'/\epsilon$ to values in good agreement with the experimental measurements.