Heavy Baryonic Decays of Λ_b \to Λη^{(\prime)} and Nonspectator Contribution

Abstract

We calculate the branching ratios of the hadronic Λ_b decays to ηand η^\prime in the factorization approximation where the form factors are estimated via QCD sum rules and the pole model. Our results indicate that, contrary to B\to Kη^{(\prime)} decays, the branching ratios for Λ_b\toΛηand Λ_b\toΛη^\prime are more or less the same in the hadronic Λ_b transitions. We estimate the branching ratio of Λ_b\toΛη^{(\prime)} to be 10.80 (10.32)\times 10^{-6} in QCD sum rules, and 2.78 (2.96)\times 10^{-6} in the pole model. We also estimate the nonfactorizable gluon fusion contribution to Λ_b\toΛη^\prime decay by dividing this process into strong and weak vertices. Our results point to an enhancement of more than an order of magnitude due to this mechanism.

16 pages, ReVTeX, 5 eps figures