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Measurement of CP violation and the B_s^0 meson decay width difference with B_s^0\to J/\psi K^+ K^- and B_s^0\to J/\psi\pi^+\pi^- decays

Abstract : The time-dependent CP asymmetry in B_s^0\to J/\psi K^+K^- decays is measured using $pp$ collision data at \sqrt{s}=7TeV, corresponding to an integrated luminosity of 1.0fb^-1, collected with the LHCb detector. The decay time distribution is characterised by the decay widths \Gamma_L and \Gamma_H of the light and heavy mass eigenstates of the B_s^0--\bar{B}_s^0 system and by a CP-violating phase \phi_s. In a sample of 27\,617 B_s^0\to J/\psi K^+K^- decays, where the dominant contribution comes from B_s^0\to J/\psi\phi\ decays, these parameters are measured to be \phi_s = 0.07 \pm 0.09 (stat) \pm 0.01 (syst) rad, \Gamma_s \equiv (\Gamma_L+\Gamma_H)/2 = 0.663 \pm 0.005 (stat) \pm 0.006 (syst) ps^-1, \Delta\Gamma_s \equiv \Gamma_L -\Gamma_H = 0.100 \pm 0.016 (stat) \pm 0.003 (syst) & ps^-1, corresponding to the single most precise determination of \phi_s, \Delta\Gamma_s and \Gamma_s. The result of performing a combined analysis with B_s^{0} \to J/\psi \pi^+\pi^- decays gives \phi_s = 0.01 \pm 0.07 (stat) \pm 0.01 (syst) rad, \Gamma_s = 0.661 \pm 0.004 (stat) \pm 0.006 (syst) ps^-1, \Delta\Gamma_s = 0.106 \pm 0.011 (stat) \pm 0.007 (syst) & ps^-1. All measurements are in agreement with the Standard Model predictions.
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http://hal.in2p3.fr/in2p3-00811826
Contributor : Sabine Starita <>
Submitted on : Thursday, April 11, 2013 - 10:49:29 AM
Last modification on : Wednesday, September 16, 2020 - 4:18:58 PM

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R. Aaij, Y. Amhis, S. Barsuk, O. Callot, J. He, et al.. Measurement of CP violation and the B_s^0 meson decay width difference with B_s^0\to J/\psi K^+ K^- and B_s^0\to J/\psi\pi^+\pi^- decays. Physical Review D, American Physical Society, 2013, 87, pp.112010. ⟨10.1103/PhysRevD.87.112010⟩. ⟨in2p3-00811826⟩

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