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Quark off-shell contributions to $K_{L}\toγγ$ in a bound-state approach

D. Kekez·D. Klabucar·K. Kumericki·I. Picek
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Abstract

We present a new piece of evidence in favour of the importance of the quark off-shellness in the kaon. The matrix elements of the flavour-changing operators for $K_{L}\toγγ$ comply with the general behaviour of the matrix elements expected in the pairing bound-state model used here. The present calculation in essence agrees with previous chiral-quark results. The off-shell contribution turns out to be dominant (the model on-shell amplitude being at the 10% level). Compared with the chiral perturbation-theory approach, our off-shell contribution is an entirely new ${\cal{O}}(p^{4})$ {\em direct-decay} piece, whereas the non-diagonal magnetic-moment term belongs to the order ${\cal{O}}(p^{6})$.

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D. Kekez, D. Klabucar, K. Kumericki, I. Picek. 1995-01-20. Quark off-shell contributions to $K_{L}\toγγ$ in a bound-state approach. https://doi.org/10.1016/0370-2693(95)00100-y

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