Heavy Baryonic Decays of Λb → Λη⁽′⁾ and Nonspectator Contribution

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We calculate the branching ratios of the hadronic Λb decays to ηand η′ 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→ Kη⁽′⁾ decays, the branching ratios for Λb→Ληand Λb→Λη′ are more or less the same in the hadronic Λb transitions. We estimate the branching ratio of Λb→Λη⁽′⁾ to be 10.80 (10.32)× 10⁻⁶ in QCD sum rules, and 2.78 (2.96)× 10⁻⁶ in the pole model. We also estimate the nonfactorizable gluon fusion contribution to Λb→Λη′ 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.