Exotic Hadrons in the $Λ_b \rightarrow J/ψ\ ϕ\ Λ$ Decay
We study the weak decay of the $Λ_b$ baryon into $J/ψ ϕ Λ$, a process that is particularly well suited to analyze the physics of some of the recently observed or theoretically predicted exotic hadrons, as one expects to see their signature in all three final two-body channels. In the $J/ψ\, ϕ$ invariant mass spectrum we study the interplay between the $X(4140)$ and the $X(4160)$ resonances. The $J/ψ\, Λ$ mass spectrum may help to identify the strange partner of the hidden-charm pentaquark recently observed by the LHCb collaboration, the existence of which has been predicted by a chiral unitary approach. We conclude that this strange pentaquark has a good chance of experimental detection if it is present in the range between $4450-4500$ MeV. Finally, in the $ϕ\, Λ$ spectrum we expect a contribution from a dynamically generated resonance at around $2160$ MeV, but with the present model parameters there is little chance for its experimental detection.