Leading logarithms of the b quark mass in inclusive B → Xs γ decay
Abstract
Part of the order αs correction to the inclusive B → Xs γ photon spectrum is enhanced by log(mb2ms2). We discuss its origin and sum the corrections proportional to [αs log(mb2μ2)]n to all orders. These are the calculable leading logarithms in the parton fragmentation functions of a quark or gluon into a photon. Although the gluon fragmentation into a photon starts only at order αs2, its contribution is of the same order as the s quark's in the leading log sum. For not too small values of the photon energy, the resummation.yields a moderate suppression. In the standard model, the coefficient of the operator whose matrix element gives rise to such terms is small. A measurement of the photon spectrum around 1 GeV would provide a theoretically clean determination of C8, the Wilson coefficient of the b → s g operator.
Additional Information
@ 1995 Elsevier Science B.V. Received 12 July 1995. Work supported in part by the U.S. Dept. of Energy under Grant no. DE-FG03-92-ER 40701. We thank Mark Wise for many useful discussions and Peter Cho and Ira Rothstein for helpful conversations. After this work was completed we received the preprint [ 171, which also discusses the loss contribution to the photon spectrum. Our result in Eq. (2.3) agrees with Eq. (18) of [ 171. Ref. [ 171 mentions that soft photons could be summed to eliminate the singularity near E, = 0, but our main point is that resumming collinear gluons is relevant for any photon energy.Additional details
- Eprint ID
- 70362
- DOI
- 10.1016/0370-2693(95)00962-K
- Resolver ID
- CaltechAUTHORS:20160915-085815399
- DE-FG03-92-ER 40701
- Department of Energy (DOE)
- Created
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2016-09-29Created from EPrint's datestamp field
- Updated
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2021-11-11Created from EPrint's last_modified field