Four-quark Bound States in Chiral SU(3) Quark Model

TL;DR

This study investigates the existence of heavy-light four-quark bound states using the chiral SU(3) quark model, finding a stable bound state for the $bbar{n}ar{n}$ configuration and near-threshold states for $ccar{n}ar{n}$.

Contribution

It demonstrates the formation of bound four-quark states within the chiral SU(3) quark model, highlighting the role of chiral interactions in binding energies.

Findings

Bound state for $bbar{n}ar{n}$ with $J^{P}=1^{+},I=0$

Near-threshold state for $ccar{n}ar{n}$

Weakly bound $bbar{n}ar{n}$ state without chiral interactions

Abstract

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.