Observation of CP Violation in $B^0 \to K^+\pi^-$ and $B^0 \to \pi^+\pi^-$

Abstract : We report observations of CP violation in the decays B0 -> K+pi- and B0 -> pi+pi- in a sample of 383 million Y4S -> BBbar events. We find 4372 +/- 82 B0 -> K+pi- decays and measure the direct CP-violating charge asymmetry Akpi = -0.107 +/- 0.018 (stat) +0.007-0.004 (syst), which excludes the CP-conserving hypothesis with a significance of 5.5 standard deviations. In the same sample we find 1139 +/- 49 B0 -> pi+pi- decays and measure the CP-violating asymmetries Spipi = -0.60 +/- 0.11 (stat) +/- 0.03 (syst) and Cpipi = -0.21 +/- 0.09 (stat) +/- 0.02 (syst). CP conservation in B0 -> pi+pi- (Spipi=Cpipi=0) is excluded at a confidence level 1-C.L. = 8 * 10^{-8}, corresponding to 5.4 standard deviations.
Document type :
Journal articles

http://hal.in2p3.fr/in2p3-00137616
Contributor : Claudine Bombar <>
Submitted on : Tuesday, March 20, 2007 - 5:33:00 PM
Last modification on : Sunday, June 20, 2021 - 3:34:51 AM

Citation

B. Aubert, M. Bona, D. Boutigny, Y. Karyotakis, J.P. Lees, et al.. Observation of CP Violation in $B^0 \to K^+\pi^-$ and $B^0 \to \pi^+\pi^-$. Physical Review Letters, American Physical Society, 2007, 99, 021603 (7p.). ⟨10.1103/PhysRevLett.99.021603⟩. ⟨in2p3-00137616⟩

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