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The J/ψ particle is a subatomic particle, also known as the J/ψ meson or charmonium. It is a meson, which is a composite particle made up of a quark and an antiquark. The J/ψ particle is made up of a charm quark and an anti-charm quark. It was discovered in 1974 by Samuel C. C. Ting and Burton Richter, who were awarded the Nobel Prize in Physics for their work.