PHOTON ENERGY-SPECTRUM IN B-]X(S)+GAMMA AND COMPARISON WITH DATA

A comparison of the inclusive photon energy spectrum in the radiative decay B --> X(s) + gamma, measured recently by the CLEO Collaboration, with the standard model is presented, using a B-meson wave function model and improving earlier perturbative QCD-based computations of the same. The dependence of the photon energy spectrum on the non-perturbative model parameters, p(F), the b-quark Fermi momentum in the B hadron, and m(q), the spectator quark mass, is explicitly shown, allowing a comparison of these parameters with the ones obtained from the analysis of the lepton energy spectrum in semileptonic B decays. Taking into account present uncertainties, we estimate BR(B --> X(s) + gamma) = (2.55 +/- 1.28) x 10(-4) in the standard model, assuming \V-ts\/\V-cb\ = 1.0. Comparing this with the CLEO measurement BR(B --> X(s) + gamma) = (2.32 +/- 0.67) x 10(-4) implies \V-ts\/\V-cb\ = 1.1 +/- 0.43, in agreement with the CKM unitarity.