Investigation of CP violation in $B^{0} \to J/\psi K_{S}^{0}$ decays at LEP with the OPAL detector

An investigation of CP violation is performed using a total of 24 candidates for B/sup 0/ to J/ psi K/sub S//sup 0/ decay, with a purity of about 60%. These events were selected from 4.4 million hadronic Z/sup 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/sup 0/ of B/sup 0/, is developed to allow a first direct study of the time dependent CP asymmetry that, in the standard model, is sin 2 beta . The result is sin 2 beta =3.2/sub -2.0//sup +1.8/+or-0.5. (6 refs).