Gold-plated mode reexamined:: sin(2β) and B0→J/ΨKS in the standard model -: art. no. 036006

We study the corrections to the determination of sin(2beta) from the time dependent CP asymmetry of B-0-->J/PsiK(S) which arise in the standard model. Although a precise prediction of these corrections is not possible we find that they are indeed extremely small, of the order of less than a per mil of the observed value. This means in turn that any deviation visible at the B factories will be a clear signal for new physics.