J/psi particle

[jey-sahy, -psahy]

Origin of J/psi particle

First recorded in 1975–80; see J particle, psi particle
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

British Dictionary definitions for j/psi particle

J/psi particle

noun
  1. a type of elementary particle (meson) thought to be formed from charmed quarksSee 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

j/psi particle in Science

J/psi particle

[jā, -psī]
  1. 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.