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Sigma (particle)



Sigma Baryon
Classification
Subatomic particle
Fermion, Hadron
Baryon
Sigma
Properties
Symbol: Σ + Σ0 Σ
Mass (MeV/c2): 1189.33±0.07 1192.642±0.024 1197.449±0.030
Electric Charge: +e 0 -e
I(Iz), JP: 1(+1), ½+ 1(0), ½+ 1(-1), ½+
Quark Composition: uus uds dds

Sigma particles are baryons composed of one strange quark and a combination of up and down quarks, arranged in an isospin 1 state. These are hyperons.

Additional recommended knowledge

The symbol Σ is also used for similar heavier particles containing charm and bottom quarks. They are, by definition, not hyperons.

Sigma particles
Particle Symbol Makeup Rest mass
MeV/c2
Spin S C B Mean lifetime
s
Decays to
Sigma Σ+ uus 1189.4 1/2 -1 0 0 0.8×10-10 π0 + p
or π+ + n
Sigma Σ0 uds 1192.5 1/2 -1 0 0 6×10-20 Λ0 + γ
Sigma Σ- dds 1197.4 1/2 -1 0 0 1.5×10-10 π- + n
bottom Sigma Σ+b uub 1/2 0 0 -1 Λ0b + π+
bottom Sigma Σ-b ddb 1/2 0 0 -1 Λ0b + π-

See also

References

  • Particle Data Group: W.-M. Yao et al., J. Phys G 33, 1 (2006).
  • The Sigma Baryon. HyperPhysics.
  • "CDF finds exotic relatives of protons and neutrons". Fermilab Today. 2006-10-23
 
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Sigma_(particle)". A list of authors is available in Wikipedia.
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