the lightest of the psi particles, the first particle to be discovered that contains a charmed quark.
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British Dictionary definitions for J/psi particle
a type of elementary particle (meson) thought to be formed from charmed quarks: See charm 1 (def. 7)
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for J/psi particle
An electrically neutral meson having a mass 6,060 times that of the electron and a mean lifetime of approximately 1 X 10-20 seconds. The observation of this unusually long lifetime, in 1974, is what led to the hypothesis that other quarks existed in addition to the up, down, and strange quarks. It was the first firm experimental evidence for the charm quark and is considered to be a charm-anticharm quark pair. Also called J particle psi particle See Table at subatomic particle.
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