# $b \rightarrow s\gamma$ using a sum of exclusive modes

Abstract : This paper describes preliminary results on the inclusive process b --> s gamma obtained from 20.7 fb^-1 of data recorded with the BaBar detector during 1999-2000. Signal event yields are found from a combination of twelve exclusive decay channels after subtracting continuum and BBbar backgrounds. Cross-feed from incorrectly reconstructed b --> s gamma events is also removed. Branching fractions in bins of hadronic mass are calculated using corrected Monte Carlo signal efficiencies; this is equivalent to measuring the gamma energy spectrum. We measure the first moment of the gamma energy spectrum constraining the HQET parameter LambdaBar = (0.37 +/- 0.09 (stat) +/- 0.07 (syst) +/- 0.10 (model)) GeV/c^2. A fit to the hadronic mass spectrum gives B(b --> s gamma) = (4.3 +/- 0.5 (stat) +/- 0.8 (syst) +/- 1.3 (model))x 10^-4 for the inclusive branching fraction. We also constrain the HQET parameter lambda_1.
Document type :
Conference papers

http://hal.in2p3.fr/in2p3-00012419
Contributor : Claudine Bombar <>
Submitted on : Tuesday, January 14, 2003 - 2:59:58 PM
Last modification on : Wednesday, January 6, 2021 - 6:22:02 PM

### Citation

B. Aubert, D. Boutigny, J.M. Gaillard, A. Hicheur, Y. Karyotakis, et al.. $b \rightarrow s\gamma$ using a sum of exclusive modes. International Conference on High Energy Physics 31 ICHEP 2002, Jul 2002, Amsterdam, Netherlands. pp.1-21. ⟨in2p3-00012419⟩

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