Analysis of the channel $\lambda_b \to \lambda J/\psi$

A first study of the LHCb sensitivity to the decay Lambda_b -> Lambda JPsi (including also AntiLambda_b -> AbtiLambda JPsi) is presented in this paper. A signal sample of 280,000 events allows to estimate the different efficiencies of this channel. The global efficiency (included first HLT simulation) reachs 0.45% and the annual yield is expected to be about 18*10^3 selected events. A study of the background is performed. For inclusive bb, a B/S ratio of 0.30, based on an analysis of 12.8 millions events(DC04v1), has been estimated. Specific background contributions are negligible.