Pentaquark States From Bound-state Approach

In 2015,the LHCb reported the discovery of pentaquarks and gave the corresponding mass and quantum number.In this paper,using the bound-state approach based on Skyrme model,considering the chiral partner of heavy meson,the quantum number and mass of the five quark states found by LHCb are explained,and the pentaquarks with other quantum numbers and masses are given.Although the Skyrme model is only a simple extension of the nonlinear σ model,the soliton solution of the model can be used to describe baryons such as neutrons.For baryons with s quark or heavy quark,the bound state method based on the Skyrme model can be used.Its physical image is that the solitons and mesons form a bound state through interaction.The mesons bound together with the solitons can be one or more,which makes it possible to explain the richer multi-quark states.In this paper,we first introduce the Skyrme model and the bound-state approach based on the Skyrme model.Then we introduce the heavy quark symmetry and discuss how to construct the Lagrangian for the interactions of the heavy meson and the Goldstone boson.Finally,considering the chiral partner,the five-quark state discovered by LHCb is explained and predicted by the bound state method.