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Investigation of CP violation in B^0 -> J/psi K^0_S decays at LEP

The OPAL Collaboration·K. Ackerstaff et al
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Abstract

An investigation of CP violation was performed using a total of 24 candidates for B^0 -> J/psi K^0_S decay, with a purity of about 60%. These events were selected from 4.4 million hadronic Z^0 decays recorded by the OPAL detector at LEP. An analysis procedure, involving techniques to reconstruct the proper decay times and tag the produced b-flavours, B^0 or B^0(bar), has been developed to allow a first direct study of the time dependent CP asymmetry that, in the Standard Model, is sin(2beta). The result is sin(2beta) = 3.2_{-2.0}^{+1.8} +/- 0.5, where the first error is statistical and the second systematic. This result is used to determine probabilities for different values of sin(2beta) in the physical region from -1 to +1.

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The OPAL Collaboration, K. Ackerstaff et al. 1998-01-23. Investigation of CP violation in B^0 -> J/psi K^0_S decays at LEP. https://doi.org/10.1007/s100520050284

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