Abstract
The hidden charm pentaquark state Pc (4450), observed recently by the LHCb collaboration in the Λb →J/ψK − p decay, may be of molecular nature, as advocated by some unitary approaches that also predict pentaquark partners in the strangeness S=−1 sector. In this work we argue that a hidden-charm strange pentaquark could also be seen in the decay of theΛb , but through the J/ψη Λ decay mode, by studying the invariant mass spectrum of J/ψ Λ pairs.In our model we assume a standard weak decay topology, then incorporate the hadronization process and final state interaction effects, and we find that the J/ψη Λ final state is populated with the strength similar to that of the J/ψK− p . We have studied the dependence of our results on reasonable changes in the parameters of the models as well as on the unknown properties of the speculated hidden charm strange pentaquark. We have observed that, while there appear changes in the position of the peak and in the shapes of the distributions, a resonance signal in the J/ψ Λ invariant mass spectrum is clearly seen in all the cases. This gives us confidence that such an experimental study could result into a successful proof of the existence of this new state.
Highlights
The LHCb collaboration reported recently two exotic structures in the invariant J/ψp mass spectrum of the Λ0b → J/ψK− p process
In this work we argue that a hidden-charm strange pentaquark could be seen in the decay of the Λb, but through the J/ψηΛ decay mode, by studying the invariant mass spectrum of J/ψΛ pairs
In our model we assume a standard weak decay topology, incorporate the hadronization process and final state interaction effects, and we find that the J/ψηΛ final state is populated with the strength similar to that of the J/ψK− p
Summary
The LHCb collaboration reported recently two exotic structures in the invariant J/ψp mass spectrum of the Λ0b → J/ψK− p process. Hidden charm baryon states with similar characteristics of the states reported had already been predicted, employing a molecular picture [3–7] or a quark model approach [8, 9]. The study of the Λb → J/ψ ηΛ decay follows the same approach as that presented in [11, 16] for Λb → J/ψ K− p [14, 17] At quark level, both processes are identical and proceed through the transition diagram depicted, where we can see the W-exchange weak process transforming the b quark into ccs, followed by the hadronization of a pair of quarks which eventually produces a meson and a baryon, in addition to the J/ψ.
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