Article 3 - Abstract
J. O. Eeg, K. Kumericki and I. Picek, On the short-distance
dispersive two-photon K_L -> mu^+ mu^- amplitude,
Eur. Phys. J. C 1 (1998) 3/4, 547-561
(Bielefeld preprint BI-TP 96/08, Oslo preprint Oslo-TP-2-96 and
Zagreb preprint ZTF-96/03, also hep-ph/9605337)
Abstract
We present a full account of the two-loop, two-photon mediated
short-distance dispersive K_L \rightarrow\mu^+\mu^- decay amplitude.
QCD corrections change this amplitude considerably compared to the pure
electroweak case. The obtained amplitude is of order half of the one
loop based weak short-distance contribution, and has the same sign. In
combination with the recent measurement, the hereby completed Standard
Model prediction of the short-distance amplitude provides a constraint
on the otherwise uncertain long-distance dispersive amplitude.
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