Precision Measurement of the B to X_s \gamma Photon Energy Spectrum, Branching Fraction, and Direct CP Asymmetry A_{CP}(B to X_{s+d}\gamma

Abstract : The photon spectrum in the inclusive electromagnetic radiative decays of the $B$ meson, $B \to X_{s} \gamma$ plus $B \to X_{d} \gamma$, is studied using a data sample of $(382.8 \pm 4.2) \times 10^6$ $\Upsilon(4S) \to B\overli\ ne{B}$ decays collected by the \babar\ experiment at SLAC. The spectrum is used to extract the branching fraction ${\cal B}(B \to X_{s} \gamma)=(3.21 \pm 0.33)\times 10^{-4}$ for $E_{\gamma}>1.8 \gev$ and the direct CP asymmetry $A_{CP}(B \to X_{s+d} \gamma)=0.057 \pm 0.063$. The effects of detector resolution and Doppler smearing are unfolded to measure the photon energy spectrum in the $B$ meson rest frame.
Document type :
Journal articles
Physical Review Letters, American Physical Society, 2012, 109, pp.191801. <10.1103/PhysRevLett.109.191801>

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Submitted on : Thursday, July 12, 2012 - 2:26:20 PM
Last modification on : Tuesday, October 11, 2016 - 3:21:33 PM

Citation

J. P. Lees, V. Poireau, V. Tisserand, D. Bernard, M. Verderi, et al.. Precision Measurement of the B to X_s \gamma Photon Energy Spectrum, Branching Fraction, and Direct CP Asymmetry A_{CP}(B to X_{s+d}\gamma. Physical Review Letters, American Physical Society, 2012, 109, pp.191801. <10.1103/PhysRevLett.109.191801>. <in2p3-00717277>

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