Pion-induced production of hidden-charm pentaquarks Pc(4312),Pc(4440), and Pc(4457)

Abstract

The production of the hidden-charm pentaquarks via a pion-induced reaction on a proton target is investigated within an effective Lagrangian approach. Three experimentally observed states, Pc(4312), Pc(4440), and Pc(4457), are considered in calculation, and the Reggeized t-channel meson exchange is considered as main background for the reaction π−p→J/ψn. The numerical results show that the experimental data of the total cross section at W≃5 GeV can be well explained by the contribution from the Reggeized t channel with reasonable cutoff. If the branching ratios Br[Pc→J/ψN]≃3% and Br[Pc→πN]≃0.05% are taken, the average value of the cross section from the Pc(4312) is about 1.2 nb/100 MeV, which is consistent with existing rude data at near-threshold energies. The results indicate that the branching ratios of the Pc state decays into J/ψN and πN should be small. The differential cross section shows a sharp increase at extreme forward angles due to the Reggeized t-channel contribution while the contributions from the Pc states are relatively flat. High-precision experimental measurement on the reaction π−p→J/ψn at near-threshold energies is suggested to confirm the LHCb hidden-charm pentaquarks as genuine states, and such measurement is also helpful to understand the origins of these resonance structures.