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Published November 9, 2012 | Published
Journal Article Open

Precision Measurement of the B → X_sγ Photon Energy Spectrum, Branching Fraction, and Direct CP Asymmetry A_(CP)(B → X_(s+d)γ)


The photon spectrum in the inclusive electromagnetic radiative decays of the B meson, B → X_sγ plus B → X_dγ, is studied using a data sample of (382.8±4.2)×10^6Υ(4S) → BB decays collected by the BABAR experiment at SLAC. The spectrum is used to extract the branching fraction B(B → X_sγ)=(3.21±0.33)×10^(-4) for E_γ > 1.8  GeV and the direct CP asymmetry A_(CP)(B → X_(s+d)γ)=0.057±0.063. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the B meson rest frame.

Additional Information

© 2012 American Physical Society. Received 12 July 2012; published 9 November 2012. We are grateful for the excellent luminosity and machine conditions provided by our PEP-II colleagues, and for the substantial dedicated effort from the computing organizations that support BABAR. The collaborating institutions wish to thank SLAC for its support and kind hospitality. This work is supported by DOE and NSF (USA), NSERC (Canada), CEA and CNRS-IN2P3 (France), BMBF and DFG (Germany), INFN (Italy), FOM (The Netherlands), NFR (Norway), MES (Russia), MICIIN (Spain), and STFC (United Kingdom). Individuals have received support from the Marie Curie EIF (European Union) and the A. P. Sloan Foundation (USA).

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Published - PhysRevLett.109.191801.pdf


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