Strong evidence for the deconfinement of quarks comes, instead, from studying the production of charmonium - particles containing a heavy charm quark and antiquark - in nucleus-nucleus collisions. Some of the dilepton pairs seen in experiments come from the decay of charmonium. These charmonium particles (also called J/psi, chi and psi prime) have many properties that we are familiar with from the study of positronium, the bound state of an electron and positron.
A bound state consisting of a charmed quark and a charmed antiquark. A major impetus for the quark theory was the discovery in 1974 of the J/psi particle, a particle whose properties closely matched the predictions for charmonium.
Any of various elementary particles consisting of a charm quark and an antiquark.
ETYMOLOGY: From charm.
The American HeritageÂ® Dictionary of the English Language, Fourth Edition. Copyright Â© 2000 by Houghton Mifflin Company. Published by the Houghton Mifflin Company. All rights reserved.