We systematically investigate the dibaryons ${\mathrm{\Xi }}_{cc}^{(*)}{\mathrm{\Xi }}_{cc}^{(*)}$ (di-${\mathrm{\Xi }}_{cc}$) and ${\mathrm{\Xi }}_{bb}^{(*)}{\mathrm{\Xi }}_{bb}^{(*)}$ (di-${\mathrm{\Xi }}_{bb}$), with various isospin-spin configurations $I(J^P)$ in a nonrelativistic quark model. For the di-${\mathrm{\Xi }}_{cc}$ system, only the single channels ${\mathrm{\Xi }}_{cc}{\mathrm{\Xi }}_{cc}^{*}$ and ${\mathrm{\Xi }}_{cc}^{*}{\mathrm{\Xi }}_{cc}^{*}$ with $0(1^{+})$ are capable of forming deuteronlike bound states, with the $\sigma$ meson exchange playing a decisive role. Those states have binding energies of approximately $-1.5\mathrm{MeV}$ and $-3.3\mathrm{MeV}$ and sizes of 2.37 fm and 1.87 fm, respectively. The coupled channel effect in the di-${\mathrm{\Xi }}_{cc}$ system with $0(1^{+})$ enhances the attraction. As a result, this di-${\mathrm{\Xi }}_{cc}$ system can establish a deuteronlike configuration, with the binding energy of $-7.5\mathrm{MeV}$ relative to the threshold ${\mathrm{\Xi }}_{cc}{\mathrm{\Xi }}_{cc}$ and the size of approximately 1.40 fm. For the di-${\mathrm{\Xi }}_{bb}$ system, the single channels with $0(1^{+})$, $0(2^{+})$, and $0(3^{+})$ can give rise to deuteronlike bound states with binding energies ranging from $-6.1\mathrm{MeV}$ to $-14.3\mathrm{MeV}$. Additionally, the di-${\mathrm{\Xi }}_{bb}$ system with $1(0^{+})$ and $1(2^{+})$ can also establish deuteronlike bound states with binding energies of around $-0.5\mathrm{MeV}$. When considering the coupled channel effect in the di-${\mathrm{\Xi }}_{bb}$ system with $0(1^{+})$, a compact hexaquark state is formed, exhibiting a binding energy of $-21.2\mathrm{MeV}$ relative to the threshold ${\mathrm{\Xi }}_{bb}{\mathrm{\Xi }}_{bb}$ and a size of 0.53 fm. In this state, the $\pi$ meson exchange provides a very powerful attractive force. The meson exchange interactions in the quark model is dispensable in the di-${\mathrm{\Xi }}_{bb}$ bound states, except for ${\mathrm{\Xi }}_{bb}^{*}{\mathrm{\Xi }}_{bb}^{*}$ with $1(0^{+})$.

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• Multiquark bound states
• Quark model