Deciphering the XYZ States

TL;DR

This paper reviews the current understanding of exotic XYZ mesonic resonances and hidden-charm pentaquarks, focusing on their description as hadronic molecules and hadro-quarkonium systems, and discusses experimental production methods.

Contribution

It provides a concise overview of the theoretical models and recent experimental observations related to exotic multiquark states and pentaquarks.

Findings

Exotic XYZ states can be described as hadronic molecules or hadro-quarkonium.

Recent observations include hidden-charm pentaquarks.

New experimental production mechanisms are discussed.

Abstract

I give a brief account of current topics in description of exotic multiquark mesonic resonances with hidden heavy ($c$ or $b$) flavor, the so-called XYZ states, in terms of hadronic molecules and hadro-quarkonium systems. Also discussed are the recently observed hidden-charm pentaquarks including additional ways of producing them in experiments.