Dibaryons: Molecular versus Compact Hexaquarks

TL;DR

This paper reviews the experimental and theoretical understanding of dibaryons, especially the $d^*(2380)$ resonance, discussing its properties, possible compact hexaquark nature, and the broader context of molecular versus compact configurations in multi-quark systems.

Contribution

It provides a comprehensive overview of recent findings on $d^*(2380)$, highlighting evidence for its compact hexaquark structure and comparing molecular and compact models in dibaryon research.

Findings

$d^*(2380)$ is an established resonance with narrow width and deep binding.

Decay patterns support a compact hexaquark interpretation.

Evidence for molecular resonances near $ ext{Δ}(1232)N$ and $N^*(1440)N$ thresholds.

Abstract

Hexaquarks constitute a natural extension of complex quark systems like also tetra- and pentaquarks do. To this end the current status of $d^*(2380)$ in both experiment and theory is shortly reviewed. Recent high-precision measurements in the nucleon-nucleon channel and analyses thereof have established $d^*(2380)$ as an indisputable resonance in the long-sought dibaryon channel. Important features of this $I(J^P) = 0(3^+)$ state are its narrow width and its deep binding relative to the $\Delta(1232)\Delta(1232)$ 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 $d^*(2380)$ as well as new physics aspects it may bring in the future. In addition, we review the situation at the $\Delta(1232) N$ and $N^*(1440)N$ thresholds, where evidence for a number of resonances of presumably molecular nature have 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.