Pole model of B-meson decays into baryon-antibaryon pairs

We reconsider in detail the pole model for baryonic B decays, first crudely estimated by Deshpande et al. We make a complete calculation on the basis of the quark model by an extensive evaluation of strong- and weak-interaction vertices. We also consider charmed decays, and the previously lacking JP=1/2- baryon poles that lead to large parity-violating amplitudes. The strong couplings are calculated in absolute magnitude by our quark-pair-creation model in a crossed channel. The effects of unequal quark masses are fully taken into account, correcting previous published results, and introducing a large set of new calculations for baryon couplings. We emphasize the selection rules and algebraic ratios of rates that follow from either color antisymmetry of the baryon wave functions or from the pole model. We pay particular attention to the ratio of parity-conserving to parity-violating rates, as it enters in tests of CP violation involving modes such as p bar p. At the same time, we make a detailed discussion of the very principles of the pole model, which exhibits a series of yet overlooked problems: ambiguity in the choice of relativistic couplings, extrapolation of strong couplings to complex momentum transfer, and of weak baryon-baryon matrix elements to nonzero and large transfers. For both theoretical and experimental reasons, it is suggested that decays with a Δ are largely overestimated because of a basic weakness of the pole model for high spin. On the other hand, results with 1/2+ baryons in the final state share several features of the QCD-sum-rule calculation by Chernyak and Zhitnisky, while differing in detailed predictions that must await experimental test