LAUSR

Abstract In terms of P c 1 , c 2 = P c ( 4380 , 4450 ) + as the hidden charm pentaquark states to consist of c c u u d , we study the semileptonic Λ b → ( P c 1 , c 2 → ) J ∕ ψ p l − ν l decays. In our discussion, while the main contribution to Λ b → K − J ∕ ψ p is from the non-perturbative process via the doubly charmful b → c c s transition, we propose that the Λ b → P c 1 , c 2 → J ∕ ψ p transitions partly contribute to the Λ b → K − ( P c 1 , c 2 → ) J ∕ ψ p decays, in which the required c c pair is formed by the sea quarks, intrinsic charm, or both. We predict that B ( Λ b → J ∕ ψ p l − ν l ) = ( 2 . 0 4 − 1 . 57 + 4 . 82 , 1 . 7 5 − 1 . 35 + 4 . 14 ) × 1 0 − 6 for l = ( e , μ ) , which are about two orders of magnitude smaller than the observed decay of Λ b → p μ ν μ . We also explore the angular correlations for the J ∕ ψ p and l − ν l pairs. Our results of the decay branching ratios and angular asymmetries in Λ b → J ∕ ψ p l − ν l , accessible to the ongoing experiments at the LHCb, can be used to improve the understanding of the hidden charm pentaquark states.