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arXiv · hep-lat/0212008

On the effects of (partial) quenching on penguin contributions to K-> pi pi

M. Golterman·E. Pallante
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Abstract

Recently, we pointed out that chiral transformation properties of strong penguin operators change in the transition from unquenched to (partially) quenched QCD. As a consequence, new penguin-like operators appear in the (partially) quenched theory, along with new low-energy constants, which should be interpreted as a quenching artifact. Here, we extend the analysis to the contribution of the new low-energy constants to the K^0 -> pi^+ pi^- amplitude, at leading order in chiral perturbation theory, and for arbitrary (momentum non-conserving) kinematics. Using these results, we provide a detailed discussion of the intrinsic systematic error due to this (partial) quenching artifact. We also give a simple recipe for the determination of the leading-order low-energy constant parameterizing the new operators in the case of strong $LR$ penguins.

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M. Golterman, E. Pallante. 2003-06-13. On the effects of (partial) quenching on penguin contributions to K-> pi pi. https://doi.org/10.1103/physrevd.69.074503

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