First Observation of $CP$ Violation in the Decays of ${B}_{s}^{0}$ Mesons

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First Observation of $C P$ Violation in the Decays of $B_{s}^{0}$ Mesons

R. Aaij et al. (LHCb Collaboration)

Phys. Rev. Lett. 110, 221601 – Published 30 May 2013

See Synopsis: Asymmetry in Strange-Beauty Mesons

Abstract

Using $p p$ collision data corresponding to an integrated luminosity of $1.0 {fb}^{- 1}$ and collected by LHCb in 2011 at a center-of-mass energy of 7 TeV, we report the measurement of direct $C P$ violation in $B_{s}^{0} \to K^{-} π^{+}$ decays, $A_{C P} (B_{s}^{0} \to K^{-} π^{+}) = 0.27 \pm 0.04 (stat) \pm 0.01 (syst)$ , with significance exceeding 5 standard deviations. This is the first observation of $C P$ violation in the decays of $B_{s}^{0}$ mesons. Furthermore, we provide an improved determination of direct $C P$ violation in $B^{0} \to K^{+} π^{-}$ decays, $A_{C P} (B^{0} \to K^{+} π^{-}) = - 0.080 \pm 0.007 (stat) \pm 0.003 (syst)$ , which is the most precise measurement of this quantity to date.

Received 24 April 2013

DOI:https://doi.org/10.1103/PhysRevLett.110.221601

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