View source for Upsilon meson

{{Short description|Subatomic particle}}
{{Infobox particle
| name = Upsilon ({{SubatomicParticle|Upsilon}})
| image = [[Image:Upsilon peak.jpg|150px]]
| caption = A plot of the [[invariant mass]] of [[muon]] pairs, from the '''Upsilon particle''' discovery paper. The peak at about 9.5&nbsp;GeV is due to the contribution of the Upsilon meson.
| num_types = 1
| composition = {{SubatomicParticle|Bottom quark}}{{SubatomicParticle|Bottom antiquark}}
| statistics = [[Bosonic]]
| group = [[Meson]]s
| interaction = [[Strong interaction|Strong]], [[Weak interaction|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 [[elementary charge|''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. [[Flavour (particle physics)|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 [[mean lifetime|lifetime]] of {{val|1.21|e=-20|ul=s}} and a mass about {{val|9.46|ul=GeV/c2}} in the ground state.

<gallery>
File:Quark structure bottomonium.svg|Quark structure of the Upsilon meson
</gallery>

==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 quark]]s.
* The {{SubatomicParticle|link=yes|J/Psi}} particle is the analogous state made from [[charm quark]]s.
* [[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:Mesons]]
[[Category:Onia]]
[[Category:Subatomic particles with spin 1]]


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