Traces of the hidden-charm S=−1 pentaquark in the Λ_b→J/ΨηΛ decay

¹ Departament de Física Quntica i Astrofísica and Institut de Ciències del Cosmos (ICCUB), Universitat de Barcelona, Martí i Franquès 1, 08028 Barcelona, Spain
² Departamento de Física Teórica and IFIC, Centro Mixto Universidad de Valencia-CSIC Institutos de Investigación de Paterna, Aptdo.22085, 46071 Valencia, Spain

^a e-mail: vladimir@fqa.ub.edu

Published online: 22 March 2017

Abstract

The hidden charm pentaquark state P_c(4450), observed recently by the LHCb collaboration in the Λ_b→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 theΛ_b, 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, then 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. 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/ψΛ 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.