$X_0(2866)$ as a $D^{\ast }{\bar{K}}^{\ast }$ molecular state

Abstract

Very recently the LHCb Collaboration reported the discovery of two open charm tetraquark states, $X_0(2866)$ and $X_1(2904)$. In the present work, we study the $D^{(\ast )}$ and ${\bar{K}}^{(\ast )}$ interaction in the one-boson exchange model and show that the $X_0(2866)$ can be understood as a $D^{\ast }{\bar{K}}^{\ast }$ molecule with $I(J^P)=0(0^{+})$, or at least it has a large molecular component. On the other hand, the $X_1(2904)$ can not be interpreted as a molecular state. Inspired by the discovery of the $X_0(2866)$ and the fact that the $D^{\ast }{\bar{K}}^{\ast }$ interaction is strong enough to generate a bound state, we also discuss likely existence of other open charm molecules. In the meson-meson sector, two molecules near the mass thresholds of $D{D}^{\ast }$ and $D^{\ast }{D}^{\ast }$ with $I(J^P)=0(1^{+})$ are obtained, and using the heavy quark flavor symmetry their $\bar{B}{\bar{B}}^{\ast }$ and ${\bar{B}}^{\ast }{\bar{B}}^{\ast }$ counterparts are also predicted. In the meson-baryon sector, 7 open charm molecules with $I=1/2$ near the mass thresholds of $D^{(\ast )}{\Sigma }_c^{(\ast )}$ naturally appear, as dictated by the heavy quark spin symmetry.

Comments: 2 tables, 4 figures