Topical collection on clustering as a window on the hierarchical structure of quantum systems

Abstract

The question of why quantum matter exhibits hierarchical structures—from quarks, hadrons, and nuclei to atoms and molecules—is one of the fundamental problems in modern physics, yet it has not been widely discussed in a unified manner. One reason may be that each hierarchical level has traditionally been studied independently, and apparent connections between different scales were not clearly recognized. On the other hand, the concept of “clusters” may provide a common framework linking these hierarchical regimes. Namely, a cluster formed within one hierarchy can itself become a constituent particle in the next hierarchy, as nucleons in the hadronic hierarchy form atomic nuclei.