upsilon meson
{{Infobox particle
| name = Upsilon ({{SubatomicParticle|Upsilon}})
| image = 150px
| caption = A plot of the invariant mass of muon pairs, from the Upsilon particle discovery paper. The peak at about 9.5 GeV is due to the contribution of the Upsilon meson.
| num_types = 1
| composition = {{SubatomicParticle|Bottom quark}}{{SubatomicParticle|Bottom antiquark}}
| statistics = Bosonic
| group = Mesons
| interaction = Strong, weak, electromagnetic, gravity
| antiparticle = Self
| status =
| theorized =
| discovered = E288 experiment (1977)
| symbol = {{SubatomicParticle|Upsilon}}
| mass = {{val|9.46030|(26)|u=GeV/c2}}
| mean_lifetime = {{val|1.21|e=-20|ul=s}}
| decay_particle =
| electric_charge = 0 e
| spin = 1
| strangeness =
| charm =
| bottomness =
| topness =
| isospin = 0
| hypercharge = 0
| parity = -1
| c_parity = -1
}}
The Upsilon meson ({{SubatomicParticle|Upsilon}}) is a quarkonium state (i.e. flavourless meson) formed from a bottom quark and its antiparticle. It was discovered by the E288 experiment team, 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 {{val|1.21|e=-20|ul=s}} and a mass about {{val|9.46|ul=GeV/c2}} in the ground state.
File:Quark structure bottomonium.svg|Quark structure of the Upsilon meson
See also
- Oops-Leon, an erroneously-claimed discovery of a similar particle at a lower mass in 1976.
- The {{SubatomicParticle|link=yes|Phi meson}} particle is the analogous state made from strange quarks.
- The {{SubatomicParticle|link=yes|J/Psi}} particle is the analogous state made from charm quarks.
- List of mesons
References
- {{cite journal
| author=D.C. Hom| year=1977
| url=https://lss.fnal.gov/archive/1977/pub/Pub-77-058-E.pdf
| title=Observation of a Dimuon Resonance at 9.5 Gev in 400-GeV Proton-Nucleus Collisions
| journal=Physical Review Letters
| volume=39 | issue=5
| pages=252–255
| doi=10.1103/PhysRevLett.39.252
| bibcode=1977PhRvL..39..252H
|display-authors=etal}}
- {{cite journal
|author1-link=John Yoh
| author=J. Yoh
| year=1998
| url=https://lss.fnal.gov/archive/1997/conf/Conf-97-432-E.pdf
| title=The Discovery of the b Quark at Fermilab in 1977: The Experiment Coordinator's Story
| journal=AIP Conference Proceedings
| volume=424 |pages=29–42
| doi=10.1063/1.55114
| bibcode=1998AIPC..424...29Y
}}
- {{cite journal
| author=S. Eidelman et al. (Particle Data Group)
| year=2004
| journal=Physics Letters B
| volume=592 | pages=1
| title=Review of Particle Physics – {{SubatomicParticle|Upsilon}} meson
| issue=1–4
| url=https://pdg.lbl.gov/2005/listings/m049.pdf
| doi=10.1016/j.physletb.2004.06.001
|arxiv = astro-ph/0406663 |bibcode = 2004PhLB..592....1P }}
{{Particles}}
{{Authority control}}
{{DEFAULTSORT:Upsilon Meson}}
Category:Subatomic particles with spin 1
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