Measurements are presented of the CP violation observables S and C in the decays of B0 and B¯0 mesons to the J/ψKS0 final state. The data sample corresponds to an integrated luminosity of 3.0fb-1 collected with the LHCb experiment in proton-proton collisions at center-of-mass energies of 7 and 8 TeV, and contains a total of 41560 selected B0 and B¯0 decays. The analysis of the time evolution of these decays yields S=0.731±0.035(stat)±0.020(syst) and C=-0.038±0.032(stat)±0.005(syst). In the standard model, S equals sin(2β) to a good level of precision. The values are consistent with the current world averages and with the standard model expectations.
Aaij, R., Adeva, B., Adinolfi, M., Affolder, A., Ajaltouni, Z., Akar, S., … Zhong, L. (2015). Measurement of CP Violation in B0 →j/ψ KS0 Decays. Physical Review Letters, 115(3). https://doi.org/10.1103/PhysRevLett.115.031601