Exotic Discoveries in Familiar Places: Theory of the Onia and Exotics

TL;DR

This paper reviews the discovery and theoretical understanding of heavy-quark exotic hadrons like $X$, $Y$, $Z$, and $P_c$, emphasizing the dynamical diquark model as a new approach.

Contribution

It introduces the dynamical diquark picture as a novel theoretical framework for understanding heavy-quark exotics.

Findings

Diquark model offers new insights into exotic hadron structure

Summary of experimental discoveries of $X$, $Y$, $Z$, and $P_c$ states

Comparison of different theoretical models for exotics

Abstract

This brief overview presents an introduction to the heavy-quark exotic hadron candidates, $X$, $Y$, $Z$, $P_c$, believed to be tetraquark and pentaquark states. After an abridged account of their discovery, we outline the various theoretical pictures employed to describe their structure, with special focus on the new dynamical diquark picture.