| Abstract |
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The photon spectrum in B -> X_s gamma decay, where X_s is any strange
hadronic state, is studied using a data sample of (382.8\pm 4.2) \times 10^6
e^+ e^- -> Upsilon(4S) -> BBbar events collected by the BaBar
experiment at the PEP-II collider. The spectrum is used to measure
the branching fraction B(B -> X_s gamma) =
(3.21 \pm 0.15 \pm 0.29 \pm 0.08)\times 10^{-4} and the first, second,
and third moments <(E_gamma)> = 2.267 \pm 0.019 \pm 0.032 \pm 0.003 GeV,
<(E_gamma - <(E_gamma)>)^2> = 0.0484 \pm 0.0053 \pm 0.0077 \pm 0.0005 GeV^2, and
<(E_gamma - <(E_gamma)>)^3> = -0.0048 \pm 0.0011 \pm 0.0011 \pm 0.0004 GeV^3
for the range E_gamma > 1.8 GeV, where E_gamma is the
photon energy in the B-meson rest frame. Results are also presented
for narrower E_gamma ranges. In addition, the direct CP asymmetry
A_{CP}(B -> X_{s+d} gamma) is measured to be 0.057 \pm 0.063.
The spectrum itself is also unfolded to the B-meson rest frame; that is
the frame in which theoretical predictions for its shape are made.
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