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Precision measurement of CP violation in B0s→J/ψK+K− decays

Abstract : The time-dependent CP asymmetry in B0s→J/ψK+K− decays is measured using pp collision data, corresponding to an integrated luminosity of 3.0fb−1, collected with the LHCb detector at centre-of-mass energies of 7 and 8TeV. In a sample of 96 000 B0s→J/ψK+K− decays, the CP-violating phase ϕs is measured, as well as the decay widths ΓL and ΓH of the light and heavy mass eigenstates of the B0s−B¯0s system. The values obtained are ϕs=−0.058±0.049±0.006 rad, Γs≡(ΓL+ΓH)/2=0.6603±0.0027±0.0015ps−1, andΔΓs≡ΓL−ΓH=0.0805±0.0091±0.0032ps−1, where the first uncertainty is statistical and the second systematic. These are the most precise single measurements of those quantities to date. A combined analysis with B0s→J/ψπ+π− decays gives ϕs=−0.010±0.039rad. All measurements are in agreement with the Standard Model predictions. For the first time the phase ϕs is measured independently for each polarisation state of the K+K− system and shows no evidence for polarisation dependence.
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Contributor : Sabine Starita <>
Submitted on : Thursday, November 13, 2014 - 10:39:39 AM
Last modification on : Monday, February 22, 2021 - 2:00:02 PM

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R. Aaij, Y. Amhis, S. Barsuk, M. Borsato, O. Kochebina, et al.. Precision measurement of CP violation in B0s→J/ψK+K− decays. Physical Review Letters, American Physical Society, 2015, 114 (4), pp.041801. ⟨10.1103/PhysRevLett.114.041801⟩. ⟨in2p3-01082285⟩



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