Spectroscopy at BESIII: A Selected XYZ Review

Abstract

Since 2003, a new group of exotic states has been identified, commonly known as XY Z states. These exotic states are incompatible with the quark-antiquark model and, therefore, are potential candidates for tetraquarks, mesonic molecules, and hybrids (e.g., gluon-quark states). Since the BESIII experiment started colliding e + e − beams in the energy range between 2.0 and 4.9 GeV, it has been a significant contributor to deepening our knowledge of this new family of states without a clear theoretical interpretation. Some of the most recent and noteworthy results from the BESIII collaboration, along with possible interpretations, are presented.