The possibility of $QQ\bar{ q}\bar{ q}$ heavy-light four-quark bound states has been analyzed by means of the chiral SU(3) quark model, where $Q$ is the heavy quark ($c$ or $b$) and $q$ is the light quark ($u$, $d$ or $s$). We obtain a bound state for the $bb\bar{ n}\bar{ n}$ configuration with quantum number $J^{ P}=1^{ +},I=0$ and for the $cc\bar{ n}\bar{ n}$ ($J^{ P}=1^{ +},I=0$) configuration which is not bound but slightly above the $D^{ *}D^{ *}$ threshold (n is $u$ or $d$ quark). Meanwhile, we also conclude that a weakly bound state in $bb\bar{ n}\bar{ n}$ system can also be found without considering the chiral quark interactions between the two light quarks, yet its binding energy is weaker than that with the chiral quark interactions.
Categories: nucl-th