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arXiv · hep-ph/0407086

Charm mass dependence of the weak Hamiltonian in chiral perturbation theory

P. Hernandez·M. Laine
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Abstract

Suppose that the weak interaction Hamiltonian of four-flavour SU(4) chiral effective theory is known, for a small charm quark mass m_c. We study how the weak Hamiltonian changes as the charm quark mass increases, by integrating it out within chiral perturbation theory to obtain a three-flavour SU(3) chiral theory. We find that the ratio of the SU(3) low-energy constants which mediate Delta I=1/2 and Delta I=3/2 transitions, increases rather rapidly with m_c, as \sim m_c ln (1/m_c). The logarithmic effect originates from "penguin-type" charm loops, and could represent one of the reasons for the Delta I=1/2 rule.

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P. Hernandez, M. Laine. 2004-10-05. Charm mass dependence of the weak Hamiltonian in chiral perturbation theory. https://doi.org/10.1088/1126-6708%2F2004%2F09%2F018

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