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Unravelling soft components in the shape function for inclusive B decays

Hiroyuki Kawamura·Jiro Kodaira·Kazuhiro Tanaka
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Abstract

In the heavy-quark limit, the decay spectrum for radiative and semileptonic inclusive B-meson decays is determined by a universal structure function, i.e. the shape function. We study the constraints on the bilocal heavy-quark operator for the shape function from the QCD equations of motion and heavy-quark symmetry, and we obtain a new basis of nonlocal operators that reveals relevant soft components in the shape function. Those nonlocal operators represent the ``kinetic energy distribution'' of the b-quark inside the B-meson and the four-parton correlations with additional quarks and gluons. A corresponding local operator basis relevant for relating the shape function to HQET parameters is also given, and novel effects of the quark-gluon correlations are discussed.

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Hiroyuki Kawamura, Jiro Kodaira, Kazuhiro Tanaka. 2005-02-28. Unravelling soft components in the shape function for inclusive B decays. https://doi.org/10.1143/ptp.113.183

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