TTP03-23 Gold-plated mode revisited: Corrections to sin(2 beta) from B^0 --> J/Psi K_S

J/Psi K_S > We study the corrections to the determination of sin(2 beta) from the time dependent CP asymmetry of B → J/Psi K_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.