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First measurement of the CP-violating phase in $B_s^0 \to \phi \phi$ decays

Abstract : A first flavour-tagged measurement of the time-dependent CP-violating asymmetry in $B_s^0 \to \phi\phi$ decays is presented. In this decay channel, the CP-violating weak phase arises due to CP violation in the interference between $B_s^0$-$\bar{B}_s^0$ mixing and the $b \to s \bar{s} s $ gluonic penguin decay amplitude. Using a sample of $pp$ collision data corresponding to an integrated luminosity of $1.0\; fb^{-1}$ and collected at a centre-of-mass energy of $7 \rm TeV$ with the LHCb detector, $880\ \B_s^0 \to \phi\phi$ signal decays are obtained. The CP-violating phase is measured to be in the interval [-2.46, -0.76] \rm rad$ at 68% confidence level. The p-value of the Standard Model prediction is 16%.
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Contributor : Sabine Starita <>
Submitted on : Friday, March 29, 2013 - 10:43:00 AM
Last modification on : Wednesday, September 16, 2020 - 4:15:35 PM

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R. Aaij, Y. Amhis, S. Barsuk, O. Callot, J. He, et al.. First measurement of the CP-violating phase in $B_s^0 \to \phi \phi$ decays. Physical Review Letters, American Physical Society, 2013, 110, pp.241802. ⟨10.1103/PhysRevLett.110.241802⟩. ⟨in2p3-00805894⟩



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