Spin, helicity and flavour patterns in exclusive decays of bottom mesons into baryon-antibaryon pairs

I use the constituent quark model to calculate the exclusive decays of bottom mesons into ground state baryon-antibaryon pairs mediated by the weak b → c and b → u transitions. The W-exchange contributions to these decays are found to be negligible. For the W-decay contributions I find that the simple colour-flavour structure of the 1/2+ and 3/2+ ground state baryons together with the current-current nonleptonic Hamiltonian leads to many simple and testable predictions. Notable among these is the predicted vanishing of decays involving 3/2+ baryons as in anti B0(B-) → 3/2+1/2+ and anti B0(B-) → 3/2+3/2+. An experimental verification of these selection rules would test the chirality of the basic b → c and b → u transitions. I also derive predictions for the polarization of the final state baryons depending on the assumed mechanism of quark pair creation. These predictions can be checked in the cases where the final state baryons are weakly decaying spin 1/2 hyperons and charmed baryons. (orig.)