upsilon particle(redirected from Upsilon meson)
Also found in: Dictionary, Wikipedia.
upsilon particle[′əp·sə·lən ‚pärd·ə·kəl]
One of a family of elementary particles having about 10 times the mass of the proton and consisting of an atomlike combination of a bottom quark with its antiquark.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.