Nonleptonic weak decays of bottom baryons

Abstract

Cabibbo-allowed two-body hadronic weak decays of bottom baryons are analyzed. Contrary to the charmed baryon sector, many channels of bottom baryon decays proceed only through the external or internal $W$-emission diagrams. Moreover, $W$ exchange is likely to be suppressed in the bottom baryon sector. Consequently, the factorization approach suffices to describe most of the Cabibbo-allowed bottom baryon decays. We use the nonrelativistic quark model to evaluate heavy-to-heavy and heavy-to-light baryon form factors at zero recoil. When applied to the heavy quark limit, the quark model results do satisfy all the constraints imposed by heavy quark symmetry. The decay rates and up-down asymmetries for bottom baryons decaying into ${\frac{1}{2}}^{+}+P(V)$ and ${\frac{3}{2}}^{+}+P(V)$ are calculated. It is found that the up-down asymmetry is negative except for ${\ensuremath{\Omega}}_{b}\ensuremath{\rightarrow}{\frac{1}{2}}^{+}+P(V)$ decay and for decay modes with ${\ensuremath{\psi}}^{\ensuremath{'}}$ in the final state. The prediction $\mathcal{B}({\ensuremath{\Lambda}}_{b}\ensuremath{\rightarrow}J/\ensuremath{\psi}\ensuremath{\Lambda})=1.6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ for $|{V}_{\mathrm{cb}}|=0.038$ is consistent with the recent Collider Detector at Fermilab measurement. We also present estimates for ${\ensuremath{\Omega}}_{c}\ensuremath{\rightarrow}{\frac{3}{2}}^{+}+P(V)$ decays and compare with various model calculations.