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Two-loop Correction to the Leptonic Decay of Quarkonium

M. Beneke·A. Signer·V. A. Smirnov
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Abstract

Applying asymptotic expansions at threshold, we compute the two-loop QCD correction to the short-distance coefficient that governs the leptonic decay $ψ\to l^+ l^-$ of a S-wave quarkonium state and discuss its impact on the relation between the quarkonium non-relativistic wave function at the origin and the quarkonium decay constant in full QCD.

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M. Beneke, A. Signer, V. A. Smirnov. 1997-12-08. Two-loop Correction to the Leptonic Decay of Quarkonium. https://doi.org/10.1103/physrevlett.80.2535

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