Investigation of CP violation in B0 → J/ψKS0 decays at LEP
K Ackerstaff, G Alexander, J Allison, N Altekamp, KJ Anderson, S Anderson, S Arcelli, S Asai, SF Ashby, D Axen, G Azuelos, AH Ball, E Barberio, RJ Barlow, R Bartoldus, JR Batley, S Baumann, J Bechtluft, T Behnke, KW Bell Show all
European Physical Journal C | Published : 1998
An investigation of CP violation was performed using a total of 24 candidates for B0 → J/ψK0S decay, with a purity of about 60%. These events were selected from 4.4 million hadronic Z0 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, B0 or B̄0, has been developed to allow a first direct study of the time dependent CP asymmetry that, in the Standard Model, is sin 2β. The result is sin 2β = 3.2+1.8-2.0 ± 0.5 where the first error is statistical and the second systematic. This result is used to determine probabilities for different values of sin 2β in the physical region from -1 to +1.