LEADING LOGARITHMS OF THE B-QUARK MASS IN INCLUSIVE B-]X(S)GAMMA-DECAY

Part of the order alpha(s) correction to the inclusive B --> X(s) gamma photon spectrum is enhanced by log(m(b)(2)/m(s)(2)). We discuss its origin and sum the corrections proportional to [alpha(s) log(m(b)(2)/mu(2))](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 alpha(s)(2), 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 C-8, the Wilson coefficient of the b --> s g operator.