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

Abstract

Abstract The three pentaquark states, $$P_c(4312)$$ P c ( 4312 ) , $$P_c(4440)$$ P c ( 4440 ) and $$P_c(4457)$$ 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 $$\bar{D}^{(*)}\Sigma _{c}^{(*)}$$ D ¯ ( ∗ ) Σ c ( ∗ ) . In the heavy quark mass limit, the $$\Sigma _{c}^{(*)}$$ Σ c ( ∗ ) baryons can be related to the doubly charmed tetraquark states of isospin 1, i.e., $$T_{\bar{c}\bar{c}}^{(*)}$$ T c ¯ c ¯ ( ∗ ) ( $$T_{\bar{c}\bar{c}}^{0}$$ T c ¯ c ¯ 0 , $$T_{\bar{c}\bar{c}}^{1}$$ T c ¯ c ¯ 1 , $$T_{\bar{c}\bar{c}}^{2}$$ T c ¯ c ¯ 2 ), via heavy antiquark diquark symmetry, which dictates that the $$\bar{D}^{(*)}\Sigma _{c}^{(*)}$$ D ¯ ( ∗ ) Σ c ( ∗ ) interactions are the same as the $$\bar{D}^{(*)}T_{\bar{c}\bar{c}}^{(*)}$$ D ¯ ( ∗ ) T c ¯ c ¯ ( ∗ ) interactions up to heavy antiquark diquark symmetry breakings. In this work, we employ the contact-range effective field theory to systematically study the $$\bar{D}^{(*)}T_{\bar{c}\bar{c}}^{(*)}$$ D ¯ ( ∗ ) T c ¯ 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 $$\bar{\Omega }_{ccc}{p}$$ Ω ¯ ccc p system can bind by the Coulomb force, which is analogous to a hydrogenlike atom.