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On the dispersive two-photon K_L -> μ^+ μ^- amplitude

J. O. Eeg·K. Kumericki·I. Picek
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Abstract

We present a full account of the two-loop electroweak, two-photon mediated short-distance dispersive $K_L \toμ^+μ^-$ decay amplitude. QCD corrections change the sign of this amplitude and reduce it by an order of magnitude. Thus, the QCD-corrected two-loop amplitude represents only a small fraction (with the central value of 5 %) of the one-loop weak short-distance contribution, and has the same sign. In combination with a recent measurement, the standard-model prediction of the short-distance amplitude, completed in this paper, provides a constraint on the otherwise uncertain long-distance dispersive amplitude.

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J. O. Eeg, K. Kumericki, I. Picek. 1997-08-27. On the dispersive two-photon K_L -> μ^+ μ^- amplitude. https://doi.org/10.1007/s100520050102

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