Abstract
The B -> gamma l nu l decay at large energies of the photon receives a numerically important soft-overlap contribution which is formally of the next-to-leading order in the expansion in the inverse photon energy. We point out that this contribution can be calculated within the framework of heavy-quark expansion and soft-collinear effective theory, making use of dispersion relations and ...
Abstract
The B -> gamma l nu l decay at large energies of the photon receives a numerically important soft-overlap contribution which is formally of the next-to-leading order in the expansion in the inverse photon energy. We point out that this contribution can be calculated within the framework of heavy-quark expansion and soft-collinear effective theory, making use of dispersion relations and quark-hadron duality. The softoverlap contribution is obtained in a full analogy with the similar contribution to the gamma*gamma -> pi it transition form factor. This result strengthens the case for using the B -> gamma l nu l decay to constrain the B-meson distribution amplitude and determine its most important parameter, the inverse moment lambda(B). (C) 2012 Elsevier B.V. All rights reserved.
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