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.