The photon spectrum in B→Xsγ decay, where Xs is any strange hadronic state, is studied using a data sample of (382.8±4.2)×106 e+e-→Υ(4S)→BB¯ events collected by the BABAR experiment at the PEP-II collider. The spectrum is used to measure the branching fraction B(B→Xsγ)=(3.21±0.15±0.29±0.08)×10-4 and the first, second, and third moments ⟨Eγ⟩=2.267±0.019±0.032±0.003GeV, ⟨(Eγ-⟨Eγ⟩)2⟩=0.0484±0.0053±0.0077±0.0005GeV2, and ⟨(Eγ-⟨Eγ⟩)3⟩=-0.0048±0.0011±0.0011±0.0004GeV3, for the range Eγ>1.8GeV, where Eγ is the photon energy in the B-meson rest frame. Results are also presented for narrower Eγ ranges. In addition, the direct CP asymmetry ACP(B→Xs+dγ) is measured to be 0.057±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.

Measurement of B (B→X_{s}γ), the B→X_{s}γ photon energy spectrum, and the direct CP asymmetry in B→X_{s+d}γ decays

LANCERI, LIVIO;VITALE, LORENZO;
2012

Abstract

The photon spectrum in B→Xsγ decay, where Xs is any strange hadronic state, is studied using a data sample of (382.8±4.2)×106 e+e-→Υ(4S)→BB¯ events collected by the BABAR experiment at the PEP-II collider. The spectrum is used to measure the branching fraction B(B→Xsγ)=(3.21±0.15±0.29±0.08)×10-4 and the first, second, and third moments ⟨Eγ⟩=2.267±0.019±0.032±0.003GeV, ⟨(Eγ-⟨Eγ⟩)2⟩=0.0484±0.0053±0.0077±0.0005GeV2, and ⟨(Eγ-⟨Eγ⟩)3⟩=-0.0048±0.0011±0.0011±0.0004GeV3, for the range Eγ>1.8GeV, where Eγ is the photon energy in the B-meson rest frame. Results are also presented for narrower Eγ ranges. In addition, the direct CP asymmetry ACP(B→Xs+dγ) is measured to be 0.057±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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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11368/2767938
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