engleski

Long vs. short distance dispersive two-photon K_L o mu^+ mu^- amplitude

We report on the calculation of the two-loop electroweak, two-photon mediated short-distance dispersive K_L o mu^+mu^- decay amplitude. QCD corrections change the sign of this contribution and reduce it by an order of magnitude. The resulting amplitude enables us to provide a constraint on the otherwise uncertain long-distance dispersive amplitude.

kaon decay; muon; dispersive amplitude; QCD corrections

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