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ISSN - 15507998, Physical Review D - Particles, Fields, Gravitation and Cosmology, 2005, vol. 72, p. -

Measurements of the B→Xsγ branching fraction and photon spectrum from a sum of exclusive final states

Aubert B., Barate R., Boutigny D., Couderc F., Karyotakis Y., Lees J. P., Poireau V., Tisserand V., Zghiche A., Grauges E., Palano A., Pappagallo M., Pompili A., Chen J. C., Qi N. D., Rong G., Wang P., Zhu Y. S., Eigen G., Ofte I., Stugu B., Abrams G. S., Battaglia M., Breon A. B., Brown D. N., Button-Shafer J., Cahn R. N., Charles E., Day C. T., Gill M. S., Gritsan A. V., Groysman Y., Jacobsen R. G., Kadel R. W., Kadyk J., Kerth L. T., Kolomensky Yu G., Kukartsev G., Lynch G., Mir L. M., Oddone P. J., Orimoto T. J., Pripstein M., Roe N. A., Ronan M. T., Wenzel W. A., Barrett M., Ford K. E., Harrison T. J., Hart A. J., Hawkes C. M., Morgan S. E., Watson A. T., Fritsch M., Goetzen K., Held T., Koch H., Lewandowski B., Pelizaeus M., Peters K., Schroeder T., Steinke M., Boyd J. T., Burke J. P., Chevalier N., Cottingham W. N., Cuhadar-Donszelmann T., Fulsom B. G., Hearty C., Knecht N. S., Mattison T. S., McKenna J. A., Khan A., Kyberd P., Saleem M., Teodorescu L., Blinov A. E., Blinov V. E., Bukin A. D., Druzhinin V. P., Golubev V. B., Kravchenko E. A., Onuchin A. P., Serednyakov S. I., Skovpen Yu I., Solodov E. P., Yushkov A. N., Best D., Bondioli M., Bruinsma M., Chao M., Curry S., Eschrich I., Kirkby D., Lankford A. J., Lund P., Mandelkern M., Mommsen R. K., Roethel W., Stoker D. P.

Using 88.9 million BB̄ events collected by the BABAR detector at the Υ(4S), we measure the branching fraction for the radiative penguin process B→Xsγ from the sum of 38 exclusive final states. The inclusive branching fraction above a minimum photon energy Eγ>1.9GeV is B(b→sγ)=(3.27±0.18(stat)-0.40+0.55(syst)-0.09+0.04(theory)) ×10-4. We also measure the isospin asymmetry between B- →Xsūγ and B̄0→Xsd̄γ to be Δ0-=-0.006±0.058(stat)±0.009(syst)±0.024(B̄0/B-) . The photon energy spectrum is measured in the B rest frame, from which moments are derived for different values of the minimum photon energy. We present fits to the photon spectrum and moments which give the heavy-quark parameters mb and μπ2. The fitted parameters are consistent with those obtained from semileptonic B→Xc ν decays, and are useful inputs for the extraction of |Vub| from measurements of semileptonic B→Xu ν decays. © 2005 The American Physical Society.