Hadronic molecules composed of a doubly charmed tetraquark state and a charmed meson

Abstract

The three pentaquark states, P_c(4312), P_c(4440) and P_c(4457), discovered by the LHCb Collaboration in 2019, can be arranged into a complete heavy quark spin symmetry multiplet of hadronic molecules of bar{D}^{(*)}Sigma _{c}^{(*)}. In the heavy quark mass limit, the Sigma _{c}^{(*)} baryons can be related to the doubly charmed tetraquark states of isospin 1, i.e., T_{bar{c}bar{c}}^{(*)}( T_{bar{c}bar{c}}^{0}, T_{bar{c}bar{c}}^{1}, T_{bar{c}bar{c}}^{2}), via heavy antiquark diquark symmetry, which dictates that the bar{D}^{(*)}Sigma _{c}^{(*)} interactions are the same as the bar{D}^{(*)}T_{bar{c}bar{c}}^{(*)} interactions up to heavy antiquark diquark symmetry breakings. In this work, we employ the contact-range effective field theory to systematically study the bar{D}^{(*)}T_{bar{c}bar{c}}^{(*)} systems, and we show the existence of a complete heavy quark spin symmetry multiplet of hadronic molecules composed of a doubly charmed tetraquark state and a charmed meson. These are a new kind of hadronic molecules and, if discovered, can lead to a better understanding of the many exotic hadrons discovered so far. In addition, we summarise the triply charmed hexaquark states formed by different combinations of hadrons. In particular, we show that bar{Omega }_{ccc}{p} system can bind by the Coulomb force, which is analogous to a hydrogenlike atom.