Final State Interactions in $K opipi$ Decays: $Delta I=1/2$ Rule vs. $arepsilon^prime/arepsilon$
(2017) European Physical Journal C. Particles and Fields — Vol. C77, n° 10, p. 10 (2017)
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- Abstract
- Dispersive effects from strong $pipi$ rescattering in the final state (FSI) of weak $K opipi$ decays are revisited with the goal to have a global view on their {it relative} importance for the $Delta I=1/2$ rule and the ratio $arepsilon^prime/arepsilon$ in the Standard Model (SM). We point out that this goal cannot be reached within a pure effective (meson) field approach like chiral perturbation theory in which the dominant current-current operators governing the $Delta I=1/2$ rule and the dominant density-density (four-quark) operators governing $arepsilon^prime/arepsilon$ cannot be disentangled from each other. But in the context of a dual QCD approach, which includes both long distance dynamics and the UV completion, that is QCD at short distance scales, such a distinction is possible. We find then that beyond the strict large $N$ limit, $N$ being the number of colours, FSI are likely to be important for the $Delta I=1/2$ rule but much less relevant for $arepsilon^prime/arepsilon$. The latter finding diminishes significantly hopes that improved calculations of $arepsilon^prime/arepsilon$ would bring its SM prediction to agree with the experimental data, opening thereby an arena for important new physics contributions to this ratio.
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Gérard, J.-M., & et al. (2017). Final State Interactions in $K opipi$ Decays: $Delta I=1/2$ Rule vs. $arepsilon^prime/arepsilon$. European Physical Journal C. Particles and Fields, C77(10), 10. https://doi.org/10.1140/epjc/s10052-016-4586-7 (Original work published 2017)