The Decay Rate of J/ψ to Λc + (Σ+)over-bar in and beyond the Standard Model

With rapid growth of the database of the BES III and the proposed super flavor factory, measurement of the rare J/psi decays may be feasible, especially the weak decays into baryon final states. In this work, we study the decay rate of J/psi to Lambda(c) (Sigma(+)) over bar in the standard model (SM) and physics beyond the SM (here we use the unparticle model as an example). The quark-pair-creation model is employed to describe the creation of a pair of q (q) over bar from a vacuum. We find that the rate of J/psi -> Lambda(c) + (Sigma(+)) over bar is of the order of 10(-10) in the SM, whereas the contribution of the unparticle is too small to be substantial. Therefore if a large branching ratio is observed, it must be due to new physics beyond the SM, but by no means the unparticle.