Hadronic molecules and multiquark states

Abstract

In this text different theoretical approaches towards multi-quark states are introduced, namely hadrocharmonia, compact tetraquarks and hadronic molecules. The predictions derived from either of them are contrasted with current and possible future observations. The focus is on doubly heavy systems, but singly heavy and light systems are mentioned briefly as well.

Comments: 23 pages, 10 figures., commissioned article for the Encyclopedia of Particle Physics