Sigma baryon

Sigma baryon

The Sigma baryons are a family of subatomic hadron particles which have a +2, +1 or −1 elementary charge or are neutral. They are baryons containing three quarks: two up and/or down quarks, and one third quark, which can be either a strange (symbols Σ+, Σ0, Σ), a charm (symbols Σ++
c
, Σ+
c
, Σ0
c
), a bottom quark (symbols Σ+
b
, Σ0
b
, Σ
b
) or a top quark (symbols Σ++
t
, Σ+
t
, Σ0
t
) quark. However, the top Sigmas are not expected to be observed as the Standard Model predicts the mean lifetime of top quarks to be roughly 5×10−25 s.[1] This is about 20 times shorter than the timescale for strong interactions, and therefore it does not form hadrons.

List

The symbols encountered in these lists are: I (isospin), J (total angular momentum), P (parity), u (up quark), d (down quark), s (strange quark), c (charm quark), t (top quark), b (bottom quark), Q (charge), B (baryon number), S (strangeness), C (charmness), B′ (bottomness), T (topness), as well as other subatomic particles (hover for name).

Antiparticles are not listed in the table; however, they simply would have all quarks changed to antiquarks, and Q, B, S, C, B′, T, would be of opposite signs. I, J, and P values in red have not been firmly established by experiments, but are predicted by the quark model and are consistent with the measurements.[2][3]

JP = 12+ Sigma baryons

JP = 12+ Sigma baryons
Particle name Symbol Quark
content
Rest mass (MeV/c2) I JP Q (e) S C B' T Mean lifetime (s) Commonly decays to
Sigma[4] Σ+ uus 1,189.37 ± 0.07 1 12+ +1 −1 0 0 0 8.018 ± 0.026 × 10−11 p+ + π0 or

n0 + π+

Sigma[5] Σ0 uds 1,192.642 ± 0.024 1 12+ 0 −1 0 0 0 7.4 ± 0.7 × 10−20 Λ0 + γ
Sigma[6] Σ dds 1,197.449 ± 0.030 1 12+ −1 −1 0 0 0 1.479 ± 0.011 × 10−10 n0 + π
charmed Sigma[7] Σ++
c
(2455)
uuc 2,454.02 ± 0.18 1 12 + +2 0 +1 0 0 3.0 ± 0.4 × 10−22 Λ+
c
+ π+
charmed Sigma[7] Σ+
c
(2455)
udc 2,452.9 ± 0.4 1 12 + +1 0 +1 0 0 >1.4 × 10−22 Λ+
c
+ π0
charmed Sigma[7] Σ0
c
(2455)
ddc 2,453.76 ± 0.18 1 12 + 0 0 +1 0 0 3.0 ± 0.5 × 10−22 Λ+
c
+ π
bottom Sigma[8] Σ+
b
(?)
uub 5,807.8+3.7
−3.9
1 12 + +1 0 0 −1 0 Unknown Λ0
b
+ π+ (seen)
bottom Sigma Σ0
b
(?)
udb Unknown 1 12 + 0 0 0 −1 0 Unknown Unknown
bottom Sigma[8] Σ
b
(?)
ddb 5,815.2 ± 2.7 1 12 + −1 0 0 −1 0 Unknown Λ0
b
+ π (seen)
Top Sigma Σ++
t
uut 1 12 + +2 0 0 0 +1
Top Sigma Σ+
t
udt 1 12 + +1 0 0 0 +1
Top Sigma Σ0
t
ddt 1 12 + 0 0 0 0 +1

^ Particle currently unobserved, but predicted by the standard model.
[a] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħΓ is given instead.
[b] ^ The specific values of the name has not been decided yet, but will likely be close to Σ
b
(5810).

JP = 32+ Sigma baryons

JP = 32+ Sigma baryons
Particle name Symbol Quark
content
Rest mass (MeV/c2) I JP Q (e) S C B' T Mean lifetime (s) Commonly decays to
Sigma[9] Σ∗+(1385) uus 1,382.8 ± 0.4 1 32+ +1 −1 0 0 0 1.84 ± 0.04 × 10−23 Λ0 + π+ or

Σ+ + π0 or
Σ0 + π+

Sigma[9] Σ∗0(1385) uds 1,383.7 ± 1.0 1 32+ 0 −1 0 0 0 1.8 ± 0.3 × 10−23 Λ0 + π0 or

Σ+ + π or
Σ0 + π0

Sigma[9] Σ∗−(1385) dds 1,387.2 ± 0.5 1 32+ −1 −1 0 0 0 1.67 ± 0.09 × 10−23 Λ0 + π or

Σ0 + π or
Σ + π0 or

charmed Sigma[10] Σ∗++
c
(2520)
uuc 2,518.4 ± 0.6 1 32 + +2 0 +1 0 0 4.4 ± 0.6 × 10−23 Λ+
c
+ π+
charmed Sigma[10] Σ∗+
c
(2520)
udc 2,517.5 ± 2.3 1 32 + +1 0 +1 0 0 >3.9 × 10−23 Λ+
c
+ π0
charmed Sigma[10] Σ∗0
c
(2520)
ddc 2,518.0 ± 0.5 1 32 + 0 0 +1 0 0 4.1 ± 0.5 × 10−23 Λ+
c
+ π
bottom Sigma Σ∗+
b
uub Unknown 1 32 + +1 0 0 −1 0 Unknown Unknown
bottom Sigma Σ∗0
b
udb Unknown 1 32 + 0 0 0 −1 0 Unknown Unknown
bottom Sigma Σ∗−
b
ddb Unknown 1 32 + −1 0 0 −1 0 Unknown Unknown
Top Sigma Σ∗++
t
uut 1 32 + +2 0 0 0 +1
Top Sigma Σ∗+
t
udt 1 32 + +1 0 0 0 +1
Top Sigma Σ∗0
t
ddt 1 32 + 0 0 0 0 +1

^ Particle currently unobserved, but predicted by the standard model.
[c] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħΓ is given instead.

See also

References

  1. ^ A. Quadt (2006). "Top quark physics at hadron colliders".  
  2. ^ C. Amsler et al. (2008): Particle summary tables – Baryons
  3. ^ J. G. Körner et al. (1994)
  4. ^ C. Amsler et al. (2008): Σ+Particle listings –
  5. ^ C. Amsler et al. (2008): Σ0Particle listings –
  6. ^ C. Amsler et al. (2008): ΣParticle listings –
  7. ^ a b c C. Amsler et al. (2008): (2455)Σ
    c
    Particle listings –
  8. ^ a b T. Aaltonen et al. (2007a)
  9. ^ a b c C. Amsler et al. (2008): (1385)ΣParticle listings –
  10. ^ a b c C. Amsler et al. (2008): (2520)Σ
    c
    Particle listings –

Bibliography

This article was sourced from Creative Commons Attribution-ShareAlike License; GNU Free Documentation License; additional terms may apply; additional licensing terms may not be displayed on the current page, please review the citiational source for the most up to date information. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.


Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.


By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia is a registered trademark of the World Public Library Association, a non-profit organization.