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 (symbols
Σ+
b,
Σ0
b,
Σ−
b) or a top (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), 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 = 1/2+ Sigma baryons

JP = 1/2+ 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+
u

u

s
 1,189.37 ± 0.07 1 1/2+ +1 −1 0 0 0 8.018 ± 0.026 × 10−11
p+
 +
π0
 or


n0
 +
π+

Sigma[5]
Σ0
u

d

s
 1,192.642 ± 0.024 1 1/2+ 0 −1 0 0 0 7.4 ± 0.7 × 10−20
Λ0
 +
γ
Sigma[6]
Σ−
d

d

s
 1,197.449 ± 0.030 1 1/2+ −1 −1 0 0 0 1.479 ± 0.011 × 10−10
n0
 +
π−
charmed Sigma[7]
Σ++
c(2455)
u

u

c
 2,454.02 ± 0.18 1 1/2 + +2 0 +1 0 0 3.0 ± 0.4 × 10−22[a]
Λ+
c +
π+
charmed Sigma[7]
Σ+
c(2455)
u

d

c
 2,452.9 ± 0.4 1 1/2 + +1 0 +1 0 0 >1.4 × 10−22[a]
Λ+
c +
π0
charmed Sigma[7]
Σ0
c(2455)
d

d

c
 2,453.76 ± 0.18 1 1/2 + 0 0 +1 0 0 3.0 ± 0.5 × 10−22[a]
Λ+
c +
π−
bottom Sigma[8]
Σ+
b(?[b])
u

u

b
5,807.8+3.7
−3.9		 1 1/2 + +1 0 0 −1 0 Unknown
Λ0
b +
π+
 (seen)
bottom Sigma†
Σ0
b(?[b])
u

d

b
 Unknown 1 1/2 + 0 0 0 −1 0 Unknown Unknown
bottom Sigma[8]
Σ−
b(?[b])
d

d

b
 5,815.2 ± 2.7 1 1/2 + −1 0 0 −1 0 Unknown
Λ0
b +
π−
 (seen)
Top Sigma†
Σ++
t
u

u

t
 — 1 1/2 + +2 0 0 0 +1 — —
Top Sigma†
Σ+
t
u

d

t
 — 1 1/2 + +1 0 0 0 +1 — —
Top Sigma†
Σ0
t
d

d

t
 — 1 1/2 + 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 = ħ/Γ 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 = 3/2+ Sigma baryons

JP = 3/2+ 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)
u

u

s
 1,382.8 ± 0.4 1 3/2+ +1 −1 0 0 0 1.84 ± 0.04 × 10−23[c]
Λ0
 +
π+
 or


Σ+
 +
π0
 or

Σ0
 +
π+

Sigma[9]
Σ∗0
(1385)
u

d

s
 1,383.7 ± 1.0 1 3/2+ 0 −1 0 0 0 1.8 ± 0.3 × 10−23[c]
Λ0
 +
π0
 or


Σ+
 +
π−
 or

Σ0
 +
π0

Sigma[9]
Σ∗−
(1385)
d

d

s
 1,387.2 ± 0.5 1 3/2+ −1 −1 0 0 0 1.67 ± 0.09 × 10−23[c]
Λ0
 +
π−
 or


Σ0
 +
π−
 or

Σ−
 +
π0
 or

charmed Sigma[10]
Σ∗++
c(2520)
u

u

c
 2,518.4 ± 0.6 1 3/2 + +2 0 +1 0 0 4.4 ± 0.6 × 10−23[c]
Λ+
c +
π+
charmed Sigma[10]
Σ∗+
c(2520)
u

d

c
 2,517.5 ± 2.3 1 3/2 + +1 0 +1 0 0 >3.9 × 10−23[c]
Λ+
c +
π0
charmed Sigma[10]
Σ∗0
c(2520)
d

d

c
 2,518.0 ± 0.5 1 3/2 + 0 0 +1 0 0 4.1 ± 0.5 × 10−23[c]
Λ+
c +
π−
bottom Sigma†
Σ∗+
b
u

u

b
 Unknown 1 3/2 + +1 0 0 −1 0 Unknown Unknown
bottom Sigma†
Σ∗0
b
u

d

b
 Unknown 1 3/2 + 0 0 0 −1 0 Unknown Unknown
bottom Sigma†
Σ∗−
b
d

d

b
 Unknown 1 3/2 + −1 0 0 −1 0 Unknown Unknown
Top Sigma†
Σ∗++
t
u

u

t
 — 1 3/2 + +2 0 0 0 +1 — —
Top Sigma†
Σ∗+
t
u

d

t
 — 1 3/2 + +1 0 0 0 +1 — —
Top Sigma†
Σ∗0
t
d

d

t
 — 1 3/2 + 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 = ħ/Γ is given instead.

See also

References

  1. ↑ A. Quadt (2006). "Top quark physics at hadron colliders". European Physical Journal C. 48 (3): 835–1000. Bibcode:2006EPJC...48..835Q. doi:10.1140/epjc/s2006-02631-6.
  2. ↑ C. Amsler et al. (2008): Particle summary tables – Baryons
  3. ↑ J. G. Körner et al. (1994)
  4. ↑ C. Amsler et al. (2008): Particle listings –
    Σ+
  5. ↑ C. Amsler et al. (2008): Particle listings –
    Σ0
  6. ↑ C. Amsler et al. (2008): Particle listings –
    Σ−
  7. 1 2 3 C. Amsler et al. (2008): Particle listings –
    Σ
    c    (2455)
  8. 1 2 T. Aaltonen et al. (2007a)
  9. 1 2 3 C. Amsler et al. (2008): Particle listings –
    Σ
    (1385)
  10. 1 2 3 C. Amsler et al. (2008): Particle listings –
    Σ
    c    (2520)

Bibliography

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