Analysis of $DD^*$ and $\bar{D}^{(*)}Ξ_{cc}^{(*)}$ molecule by one boson exchange model based on Heavy quark symmetry

Abstract

Numerous exotic hadrons with heavy quarks have been reported in the experiments. In such states, symmetries of heavy quarks are considered to play a significant role. In particular, the superflavor symmetry, or also called the heavy quark anti-diquark symmetry is one of the interesting symmetries, which links a quark $Q$ to an anti-diquark $\bar{Q}\bar{Q}$ having the same color representation as $Q$. In this paper, we study a $\bar{D}Ξ_{cc}$ molecular state as a superflavor partner of the doubly charm tetraquark $T_{cc}$ reported by LHCb recently. $T_{cc}$ locating slightly below the $DD^*$ threshold is a candidate of the hadronic molecule. Thus by replacing the singly charm meson $D^{(*)}$ with the doubly charm baryon $Ξ_{cc}^{(*)}$, superflavor symmetry predicts the existence of the $\bar{D}^{(*)}Ξ_{cc}^{(*)}$ bound state. We employ the one boson exchange model respecting with the heavy quark spin symmetry where the parameter is obtained to reproduce the $T_{cc}$ binding energy. We apply this model with superflavor symmetry to the $\bar{D}^{(*)}Ξ_{cc}^{(*)}$ molecule and predict a bound state with $I(J^P) = 0(\frac{1}{2}^-)$. If the pentaquark state corresponding to $\bar{D}^{(*)} Ξ_{cc}^{(*)}$ molecular state is observed in future experiments as predicted in this work, it is more likely that $T_{cc}$ is a $DD^*$ molecular state.