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arXiv · hep-ex/0107061

Observation of Large CP Violation in the Neutral B Meson System

K. Abe·The Belle Collaboration
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Abstract

We present a measurement of the Standard Model CP violation parameter sin 2phi_1 based on a 29.1 fb^{-1} data sample collected at the Upsilon(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e- collider. One neutral B meson is fully reconstructed as a J/psi Ks, psi(2S) Ks, chi_c1 Ks, eta_c Ks, J/psi K_L or J/psi K^{*0} decay and the flavor of the accompanying B meson is identified from its decay products. From the asymmetry in the distribution of the time intervals between the two B meson decay points, we determine sin 2phi_1 = 0.99 +- 0.14(stat) +- 0.06(syst). We conclude that we have observed CP violation in the neutral B meson system.

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K. Abe, The Belle Collaboration. 2001-08-01. Observation of Large CP Violation in the Neutral B Meson System. https://doi.org/10.1103/physrevlett.87.091802

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