Patrick Koppenburg and Marco Pappagallo discuss the discovery of 23 exotic hadrons at the LHC, including five pentaquarks and 18 tetraquarks. These particles contain a mix of quarks including charm, up, down, and strange. The discovery of these exotic states has sparked debates among theorists and opened up new avenues for research. The unexpectedly large number of new hadrons found at the LHC and the potential for more discoveries at other facilities signal an exciting time in particle physics. The classification and understanding of these exotic hadrons pose a significant challenge to the field of hadron spectroscopy, raising questions about their composition and symmetries.
https://cerncourier.com/a-bestiary-of-exotic-hadrons/