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Upsilon particle

Upsilon (\Upsilon\,)

A plot of the invariant mass of muon pairs, from the Upsilon particle discovery paper. The peak at about 9.5 GeV represents the particle itself.
Composition: Composite:
Quarks: 1 bottom, 1 antibottom
Family: Hadron
Group: Meson
Electric charge: 0 C
Spin: 1

The Upsilon particle (\Upsilon\,) is a flavorless meson formed from a bottom quark and its antiparticle. It was discovered by the E288 collaboration, headed by Leon Lederman, at Fermilab in 1977, and was the first particle containing a bottom quark to be discovered because it is the lightest that can be produced without additional massive particles. It has a lifetime of 1.21x10-20 seconds and a mass about 10 GeV.

See also


  1. Hom, D.C., et al. (1977). "Observation of a Dimuon Resonance at 9.5 Gev in 400-GeV Proton-Nucleus Collisions". Phys. Rev. Lett. 39: 252-255.
  2. Yoh, John (1998). "The Discovery of the b Quark at Fermilab in 1977: The Experiment Coordinator's Story". AIP Conf. Proc. 424: 29-42.
  3. Technical data (pdf file) from Particle Data Group (From 2005 update of S. Eidelman et al. (2004). "Review of Particle Physics". Phys. Lett. B 592: 1.)

This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Upsilon_particle". A list of authors is available in Wikipedia.
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