Studies of polarized neutron-proton scattering at the Cooler Synchrotron (COSY) in Jülich, Germany, have new evidence for a new state in the two-baryon system. The structure, containing six valence quarks, constitutes a dibaryon and could be either an exotic compact particle or a hadronic molecule. The result answers the long-standing question of whether there are more two-baryon states than just the deuteron ground-state. This fundamental question has been awaiting an answer since at least 1964, when first Freeman Dyson and later Robert Jaffe envisaged the possible existence of non-trivial six-quark configurations.
The new resonance, with a mass of 2380 MeV, a width of 80 MeV and quantum numbers I(JP) = 0(3+), was observed in high-precision measurements carried out by the WASA-at-COSY collaboration. The mass of the new state is amazingly close to that predicted originally by Dyson.
After the recent discovery by LHCb of “tetraquark” systems – mesons consisting of two quarks and two antiquarks – the newly discovered dibaryon resonance points to configurations composed of six quarks.
"COSY confirms existence of six-quark states" – CERN Courier
"Evidence for a New Resonance from Polarized Neutron-Proton Scattering " – Physical Review Letters