# A study of time-dependent CP-violating asymmetries in $B^{0} \to J/\psi K^{0}_{S}$ and $B^{0} \to \psi(2S) K^{0}_{S}$ decays

Abstract : We present a preliminary measurement of time-dependent CP-violating asymmetries in B0 -> J/psi K0S and B0 -> psi(2S) K0S decays recorded by the BABAR detector at the PEP-II asymmetric-energy B Factory at SLAC. The data sample consists of 9.0 fb-1 collected at the Y(4S) resonance and 0.8 fb-1 off-resonance. One of the neutral B mesons, produced in pairs at the Y(4S), is fully reconstructed. The flavor of the other neutral B meson is tagged at the time of its decay, mainly with the charge of identified leptons and kaons. A neural network tagging algorithm is used to recover events without a clear lepton or kaon tag. The time difference between the decays is determined by measuring the distance between the decay vertices. Wrong-tag probabilities and the time resolution function are measured with samples of fully-reconstructed semileptonic and hadronic neutral B final states. The value of the asymmetry amplitude, sin2beta, is determined from a maximum likelihood fit to the time distribution of 120 tagged B0 -> J/psi K0S and B0 -> psi(2S) K0S candidates to be sin2beta = 0.12+/-0.37 (stat) +/- 0.09 (syst) (preliminary).
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Document type :
Conference papers
International Conference on High-Energy Physics 30 ICHEP 2000, Jul 2000, Osaka, Japan. pp.1-21
Domain :

http://hal.in2p3.fr/in2p3-00006104
Contributor : Nicole Berger <>
Submitted on : Tuesday, September 19, 2000 - 5:12:28 PM
Last modification on : Tuesday, September 19, 2000 - 5:12:28 PM

### Citation

B. Aubert, A. Boucham, D. Boutigny, I. De Bonis, J. Favier, et al.. A study of time-dependent CP-violating asymmetries in $B^{0} \to J/\psi K^{0}_{S}$ and $B^{0} \to \psi(2S) K^{0}_{S}$ decays. International Conference on High-Energy Physics 30 ICHEP 2000, Jul 2000, Osaka, Japan. pp.1-21. <in2p3-00006104>

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