2002/07/24 by The BABAR Collaboration, B. Aubert, Aubert, B.
Engineering · Physics and Astronomy · #Radar Systems and Signal Processing #hep-ex
paper · pdf · doi:10.48550/arxiv.hep-ex/0207074
21 pages, 18 postscript figures, submitted to ICHEP2002
arxiv created 2002/07/24 · arxiv updated 2009/11/30
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/c2. 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 lambda1.