Quarks in six-packs: Exotic Particle Confirmed
For decades, physicists have searched in vain for exotic bound states comprising more than three quarks. Experiments performed at Jülich's accelerator COSY have now shown that, in fact, such complex particles do exist in nature. This discovery by the WASA-at-COSY collaboration has been published in the journal Physical Review Letters. The measurements confirm results from 2011, when the more than 120 scientists from eight countries discovered for the first time strong indications for the existence of an exotic dibaryon made up of six quarks.
For a long time, physicists were only able to reliably verify two different classes of hadrons: volatile mesons comprising one quark and one antiquark and baryons consisting of three quarks. Protons and neutrons, which make up atomic nuclei, are examples of the latter. In recent years, however, there has been growing evidence for the existence of additional types of hadrons, for example, hybrids, glueballs, and multiquarks. In 1964, the physicist Freeman Dyson was the first to predict such more complex states. But any reliable verification proved impossible for many years because almost no measurements could be reproduced.
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