Dibaryons: Molecular versus Compact Hexaquarks

Hexaquarks constitute a natural extension of complex quark systems, just as tetra- and pentaquarks do. To this end, the current status of \begin{document}$d^*(2380)$\end{document} in both experiment and theory is reviewed. Recent high-precision measurements in the nucleon-nucleon channel and analyses thereof have established \begin{document}$d^*(2380)$\end{document} as an indisputable resonance in the long-sought dibaryon channel. Important features of this \begin{document}$I(J^P) = 0(3^+)$\end{document} state are its narrow width and deep binding relative to the \begin{document}$\Delta(1232)\Delta(1232)$\end{document} threshold. Its decay branchings favor theoretical calculations predicting a compact hexaquark nature of this state. We review the current status of experimental and theoretical studies on \begin{document}$d^*(2380)$\end{document} as well as new physics aspects it may bring in future. In addition, we review the situation at the \begin{document}$\Delta(1232) N$\end{document} and \begin{document}$N^*(1440)N$\end{document} thresholds, where evidence for a number of resonances of presumably molecular nature has been found – similar to the situation in charmed and beauty sectors. Finally, we briefly discuss the situation of dibaryon searches in the flavored quark sectors.