S. Prelovšek Komelj (JSI) and M. Padmanath (Mainz) find evidence for the longest-lived exotic hadron. Their article in Physical Review Letters establishes this state with an ab-initio theoretical study for the first time.

 Experiments have recently discovered exotic hadrons that consist of more than three valence quarks/antiquarks. Among these, the longest-lived and the most unique is the so-called doubly charm tetraquark, discovered by CERN’s LHCb Experiment in July 2021. It contains two charm quarks, as well as up and down antiquarks.  The published lattice QCD study establishes the existence of this exotic particle directly from the fundamental quantum field theory. The findings and inferences have important implications for understanding this particle and its likes. One of the aims is to reveal whether the mechanisms responsible for its existence are analogous to those that bind protons and neutrons to nuclei, which are in turn responsible for the energy released in nuclear fusion and fission. 

link: Signature of a Doubly Charm Tetraquark Pole in DD* Scattering on the Lattice