List of baryons

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A proton, the only baryon stable in isolation, has two up quarks and one down quark, confined via the exchange of gluons. Quark structure proton.svg
A proton, the only baryon stable in isolation, has two up quarks and one down quark, confined via the exchange of gluons.

Baryons are composite particles made of three quarks, as opposed to mesons, which are composite particles made of an equal number of quarks and antiquarks. Baryons and mesons are both hadrons, which are particles composed solely of quarks or both quarks and antiquarks. The term baryon is derived from the Greek "βαρύς" (barys), meaning "heavy", because, at the time of their naming, it was believed that baryons were characterized by having greater masses than other particles that were classed as matter.

Contents

Pentaquarks are exotic baryons composed of four quarks and one antiquark. In 2015, the LHCb collaboration at CERN definitively reported the observation of pentaquark states in the decay of bottom lambda baryons0
b
). [1] Since then, additional pentaquark states have been discovered, including new observations in 2019 and 2022. While primarily created in laboratory conditions, pentaquarks might also form naturally during neutron star formation. [2] [3] [4]

Since baryons are composed of quarks, they participate in the strong interaction. Leptons, on the other hand, are not composed of quarks and as such do not participate in the strong interaction. The best known baryons are protons and neutrons, which make up most of the mass of the visible matter in the universe, whereas electrons, the other major component of atoms, are leptons. Each baryon has a corresponding antiparticle, known as an antibaryon, in which quarks are replaced by their corresponding antiquarks. For example, a proton is made of two up quarks and one down quark, while its corresponding antiparticle, the antiproton, is made of two up antiquarks and one down antiquark.

Baryon properties

These lists detail all known and predicted baryons in total angular momentum J = 1/2 and J = 3/2 configurations with positive parity. [5]

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), b (bottom quark), Q (charge), B (baryon number), S (strangeness), C (charm), B (bottomness), as well as a wide array of subatomic particles (hover for name). (See Baryon for a detailed explanation of these symbols.)

Antibaryons are not listed in the tables; however, they simply would have all quarks changed to antiquarks, and Q, B, S, C, B, would be of opposite signs. Particles with next to their names have been predicted by the Standard Model but not yet observed. Values in parentheses have not been firmly established by experiments, but are predicted by the quark model and are consistent with the measurements. [6] [7]

 JP = 1/2+ baryons

JP = 1/2+ baryons
Particle name Symbol Quark content Rest mass (MeV/c 2) I J P Q (e) S C B Mean lifetime (s) Commonly
decays to
proton [8]
p
,
p+
,
N+

u

u

d
938.2720813(58) [a] 1/21/2++10 0 0 stable [b] unobserved
neutron [9]
n
,
n0
,
N0

u

d

d
939.5654133(58) [a] 1/21/2+0 0 0 0 (8.794±0.006)×10+2 [c]
p+
+
e
+
ν
e
lambda [10]
Λ0

u

d

s
1115.683±0.0060 1/2+0 −10 0 (2.632±0.020)×10−10
p+
+
π
or


n0
+
π0
charmed lambda [11]
Λ+
c

u

d

c
2286.46±0.140 1/2++10 +10 (2.024±0.031)×10−13see
Λ+
c
decay modes
bottom lambda [12]
Λ0
b

u

d

b
5619.6±0.17(0) (1/2+)0 0 0 −1(1.471±0.009)×10−12see
Λ0
b
decay modes
sigma [13]
Σ+

u

u

s
1189.37±0.071 1/2++1−10 0 (8.018±0.026)×10−11
p+
+
π0
or


n0
+
π+
sigma [14]
Σ0

u

d

s
1192.642±0.0241 1/2+0 −10 0 (7.4±0.7)×10−20
Λ0
+
γ
sigma [15]
Σ

d

d

s
1197.449±0.0301 1/2+−1−10 0 (1.479±0.011)×10−10
n0
+
π
charmed sigma [16]
Σ++
c
(2455)

u

u

c
2453.97±0.141 1/2++20 +10 3.48+0.37
−0.16
×10−22
[d]

Λ+
c
+
π+
charmed sigma [16]
Σ+
c
(2455)

u

d

c
2452.9±0.41 1/2++10 +10 >1.43×10−22 [d]
Λ+
c
+
π0
charmed sigma [16]
Σ0
c
(2455)

d

d

c
2453.75±0.141 1/2+0 0 +10 3.60+0.42
−0.20
×10−22
[d]

Λ+
c
+
π
bottom sigma [17]
Σ+
b

u

u

b
5810.56±0.25(1) (1/2+)+10 0 −1(1.32±0.13)×10−22 [d]
Λ0
b
+
π+
bottom sigma
Σ0
b

u

d

b
unknown (1) (1/2+) 0 0 0 −1unknown unknown
bottom sigma [17]
Σ
b

d

d

b
5815.64±0.27(1) (1/2+)−10 0 −1(1.24±0.12)×10−22 [d]
Λ0
b
+
π
xi [18]
Ξ0

u

s

s
1314.86±0.201/21/2(+)0 −20 0 (2.90±0.09)×10−10
Λ0
+
π0
xi [19]
Ξ

d

s

s
1321.71±0.071/21/2(+)−1−20 0 (1.639±0.015)×10−10
Λ0
+
π
charmed xi [20]
Ξ+
c

u

s

c
2467.94+0.17
−0.20
(1/2)(1/2+)+1−1+10 (4.56±0.05)×10−13see
Ξ+
c
decay modes
charmed xi [21]
Ξ0
c

d

s

c
2470.90+0.22
−0.29
(1/2)(1/2+)0 −1+10 (1.53±0.06)×10−13see
Ξ0
c
decay modes
charmed xi prime [22]
Ξ+
c

u

s

c
2578.4±0.5(1/2)(1/2+)+1−1+10 unknown
Ξ+
c
+
γ
(seen)
charmed xi prime [23]
Ξ0
c

d

s

c
2579.2±0.5(1/2)(1/2+)0 −1+10 unknown
Ξ0
c
+
γ
(seen)
double charmed xi [24]
Ξ++
cc

u

c

c
3621.2±0.7(1/2)(1/2+)+20 +20 unknown see
Ξ++
cc
decay modes
double charmed xi [e]
Ξ+
cc

d

c

c
unknown (1/2)(1/2+)+10 +20 unknown unknown
bottom xi [25]
or cascade B

Ξ0
b

u

s

b
5791.9±0.5(1/2)(1/2+)0 −10 −1(1.480±0.030)×10−12see
Ξ0
b
decay modes
bottom xi [25]
or cascade B

Ξ
b

d

s

b
5797.0±0.6(1/2)(1/2+)−1−10 −1(1.572±0.040)×10−12see
Ξ
b
decay modes
bottom xi prime
Ξ0
b

u

s

b
unknown (1/2)(1/2+)0 −10 −1unknown unknown
bottom xi prime
Ξ
b

d

s

b
unknown (1/2)(1/2+)−1−10 −1unknown unknown
double bottom xi
Ξ0
bb

u

b

b
unknown (1/2)(1/2+)0 0 0 −2unknown unknown
double bottom xi
Ξ
bb

d

b

b
unknown (1/2)(1/2+)−10 0 −2unknown unknown
charmed bottom xi
Ξ+
cb

u

c

b
unknown (1/2)(1/2+)+10 +1−1unknown unknown
charmed bottom xi
Ξ0
cb

d

c

b
unknown (1/2)(1/2+)0 0 +1−1unknown unknown
charmed bottom xi prime
Ξ+
cb

u

c

b
unknown (1/2)(1/2+)+10 +1−1unknown unknown
charmed bottom xi prime
Ξ0
cb

d

c

b
unknown (1/2)(1/2+)0 0 +1−1unknown unknown
charmed omega [26]
Ω0
c

s

s

c
2695.2±1.7(0) (1/2+)0 −2+10 (2.68±0.24 ± 0.10)×10−13see
Ω0
c
decay modes
bottom omega [27]
Ω
b

s

s

b
6046.1±1.7(0) (1/2+)−1−20 −11.64+0.18
−0.17
×10−12

Ω
+
J/ψ
(seen)
double charmed omega
Ω+
cc

s

c

c
unknown (0) (1/2+)+1−1+20 unknown unknown
charmed bottom omega
Ω0
cb

s

c

b
unknown (0) (1/2+)0 −1+1−1unknown unknown
charmed bottom omega prime
Ω0
cb

s

c

b
unknown (0) (1/2+)0 −1+1−1unknown unknown
double bottom omega
Ω
bb

s

b

b
unknown (0) (1/2+)−1−10 −2unknown unknown
double charmed bottom omega
Ω+
ccb

c

c

b
unknown (0) (1/2+)+10 +2−1unknown unknown
charmed double bottom omega
Ω0
cbb

c

b

b
unknown (0) (1/2+)0 0 +1−2unknown unknown

^ Particle has not yet been observed.

[a] ^ The masses of the proton and neutron are known with much better precision in daltons (Da) than in MeV/c2. In atomic mass units, the mass of the proton is 1.0072764665789(83) Da [28] whereas that of the neutron is 1.00866491606(40) Da. [29]

[b] ^ At least 1035 years. See proton decay.

[c] ^ For free neutrons; in most common nuclei, neutrons are stable.

[d] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħ/Γ is given instead.

[e] ^ There is a controversial discovery claim, disfavored by other experimental data. [30]

 JP = 3/2+ baryons

JP = 3/2+ baryons
Particle name Symbol Quark
content
Rest mass (MeV/c 2) I J P Q (e) S C B Mean lifetime (s) Commonly
decays to
delta [31]
Δ++
(1232)

u

u

u
1232±23/23/2++20 0 0 (5.63±0.14)×10−24 [h]
p+
+
π+
delta [31]
Δ+
(1232)

u

u

d
1232±23/23/2++10 0 0 (5.63±0.14)×10−24 [h]
p+
+
π0
or


n0
+
π+
delta [31]
Δ0
(1232)

u

d

d
1232±23/23/2+0 0 0 0 (5.63±0.14)×10−24 [h]
n0
+
π0
or


p+
+
π
delta [31]
Δ
(1232)

d

d

d
1232±23/23/2+−10 0 0 (5.63±0.14)×10−24 [h]
n0
+
π
sigma [32]
Σ+
(1385)

u

u

s
1382.80±0.351 3/2++1−10 0 (1.828±0.036)×10−23 [h]
Λ0
+
π+
or


Σ+
+
π0
or


Σ0
+
π+
sigma [32]
Σ0
(1385)

u

d

s
1383.7±1.01 3/2+0 −10 0 (1.83±0.26)×10−23 [h]
Λ0
+
π0
or


Σ+
+
π
or


Σ0
+
π0
sigma [32]
Σ
(1385)

d

d

s
1387.2±0.51 3/2+−1−10 0 (1.671±0.089)×10−23 [h]
Λ0
+
π
or


Σ0
+
π
or


Σ
+
π0
charmed sigma [33]
Σ++
c
(2520)

u

u

c
2518.41+0.21
−0.19
1 (3/2+)+20 +10 4.45+0.12
−0.09
×10−23
[h]

Λ+
c
+
π+
charmed sigma [33]
Σ+
c
(2520)

u

d

c
2517.5±2.31 (3/2+)+10 +10 >3.87×10−23 [h]
Λ+
c
+
π0
charmed sigma [33]
Σ0
c
(2520)

d

d

c
2518.48±0.201 (3/2+)0 0 +10 4.30+0.15
−0.11
×10−23
[h]

Λ+
c
+
π
bottom sigma [34]
Σ+
b

u

u

b
5830.32±0.27(1) (3/2+)+10 0 −1(7.0±0.4)×10−23 [h]
Λ0
b
+
π+
bottom sigma [e]
Σ0
b

u

d

b
unknown (1) (3/2+)0 0 0 −1unknown unknown
bottom sigma [34]
Σ
b

d

d

b
5834.74±0.30(1) (3/2+)−10 0 −1(6.3±0.5)×10−23 [h]
Λ0
b
+
π
xi [35]
Ξ0
(1530)

u

s

s
1531.80±0.321/23/2+0 −20 0 (7.23±0.40)×10−23 [h]
Ξ0
+
π0
or


Ξ
+
π+
xi [35]
Ξ
(1530)

d

s

s
1535.0±0.61/23/2+−1−20 0 6.6+1.3
−1.1
×10−23
[h]

Ξ0
+
π
or


Ξ
+
π0
charmed xi [36]
Ξ+
c
(2645)

u

s

c
2645.56+0.24
−0.30
(1/2)(3/2+)+1−1+10 (3.08±0.28)×10−22 [h]
Ξ+
c
+
π0
(seen)
charmed xi [36]
Ξ0
c
(2645)

d

s

c
2646.38+0.20
−0.23
(1/2)(3/2+)0 −1+10 (2.80±0.22 ± 0.16)×10−22 [h]
Ξ+
c
+
π
(seen)
double charmed xi
Ξ++
cc

u

c

c
unknown (1/2)(3/2+)+20 +20 unknown unknown
double charmed xi
Ξ+
cc

d

c

c
unknown (1/2)(3/2+)+10 +20 unknown unknown
bottom xi [37]
Ξ0
b

u

s

b
5952.3±0.6(1/2)(3/2+)0 −10 −1(7.31±1.34 ± 0.66)×10−22 [h]
Ξ
b
+
π+
(seen)
bottom xi [38]
Ξ
b

d

s

b
5955.33±0.12 ± 0.05 (1/2)(3/2+)−1−10 −1(3.99±0.78 ± 0.24)×10−22 [h]
Ξ0
b
+
π
(seen)
double bottom xi
Ξ0
bb

u

b

b
unknown (1/2)(3/2+)0 0 0 −2unknown unknown
double bottom xi
Ξ
bb

d

b

b
unknown (1/2)(3/2+)−10 0 −2unknown unknown
charmed bottom xi
Ξ+
cb

u

c

b
unknown (1/2)(3/2+)+10 +1−1unknown unknown
charmed bottom xi
Ξ0
cb

d

c

b
unknown (1/2)(3/2+)0 0 +1−1unknown unknown
omega [39]
Ω

s

s

s
1672.45±0.290 3/2+−1−30 0 (8.21±0.11)×10−11 [h]
Λ0
+
K
or


Ξ0
+
π
or


Ξ
+
π0
charmed omega [40]
Ω0
c
(2770)

s

s

c
2765.9±2.00 (3/2+)0 −2+10 unknown
Ω0
c
+
γ
bottom omega
Ω
b

s

s

b
unknown (0) (3/2+)−1−20 −1unknown unknown
double charmed omega
Ω+
cc

s

c

c
unknown (0) (3/2+)+1−1+20 unknown unknown
charmed bottom omega
Ω0
cb

s

c

b
unknown (0) (3/2+)0 −1+1−1unknown unknown
double bottom omega
Ω
bb

s

b

b
unknown (0) (3/2+)−1−10 −2unknown unknown
triple charmed omega
Ω++
ccc

c

c

c
unknown (0) (3/2+)+20 +30 unknown unknown
double charmed bottom omega
Ω+
ccb

c

c

b
unknown (0) (3/2+)+10 +2−1unknown unknown
charmed double bottom omega
Ω0
cbb

c

b

b
unknown (0) (3/2+)0 0 +1−2unknown unknown
triple bottom omega
Ω
bbb

b

b

b
unknown (0) (3/2+)−10 0 −3unknown unknown

^ Particle has not yet been observed.

[h] ^ PDG reports the resonance width (Γ). Here the conversion τ = ħ/Γ is given instead.

Baryon resonance particles

This table gives the name, quantum numbers (where known), and experimental status of baryon resonances confirmed by the PDG. [41] Baryon resonance particles (including all not the above two tables) are excited baryon states with short half lives and higher masses. Despite significant research, the fundamental degrees of freedom behind baryon excitation spectra are still poorly understood. [42] The spin-parity JP (when known) is given with each particle. For the strongly decaying particles, the JP values are considered to be part of the names, as is the mass for all resonances.

Baryon resonance particles
NucleonsΔ particlesΛ particlesΣ particlesΞ and Ω particlesCharmed particlesBottom particles
p12+****Δ(1232)32+****Λ12+****Σ+12+****Ξ012+****Λ+
c
12+****Λ0
b
12+***
n12+****Δ(1600)32+****Λ(1405)12****Σ012+****Ξ12+****Λc(2595)+12***Λb(5912)012***
N(1440)12+****Δ(1620)12****Λ(1520)32****Σ12+****Ξ(1530)32+****Λc(2625)+32***Λb(5920)032***
N(1520)32****Δ(1700)32****Λ(1600)12+***Σ(1385)32+****Ξ(1620)*Λc(2765)+*Σb12+***
N(1535)12****Δ(1750)12+*Λ(1670)12****Σ(1480)*Ξ(1690)***Λc(2860)+32+***Σ*
b
32+***
N(1650)12****Δ(1900)12***Λ(1690)32****Σ(1560)**Ξ(1820)32***Λc(2880)+52+***Ξ0
b
, Ξ
b
12+***
N(1675)52****Δ(1905)52+****Λ(1710)12+*Σ(1580)32*Ξ(1950)***Λc(2940)+32***Ξ'b(5935)12+***
N(1680)52+****Δ(1910)12+****Λ(1800)12***Σ(1620)12*Ξ(2030) 5/2?***Σc(2455)12+****Ξb(5945)032+***
N(1700)32***Δ(1920)32+***Λ(1810)12+***Σ(1660)12+***Ξ(2120)*Σc(2520)32+***Ξb(5955)32+***
N(1710)12+****Δ(1930)52***Λ(1820)52+****Σ(1670)32****Ξ(2250)**Σc(2800)***Ω
b
12+***
N(1720)32+****Δ(1940)32**Λ(1830)52****Σ(1690)**Ξ(2370)**Pc(4380)+*
N(1860)52+**Δ(1950)72+****Λ(1890)32+****Σ(1730)32+*Ξ(2500)*Ξ+
c
12+***Pc(4450)+*
N(1875)32***Δ(2000)52+**Λ(2000)*Σ(1750)12***Ξ0
c
12+***
N(1880)12+***Δ(2150)12*Λ(2020)72+*Σ(1770)12+*Ω32+****Ξ+
c
12+***
N(1895)12****Δ(2200)72***Λ(2050)32*Σ(1775)52****Ω(2250)***Ξ0
c
12+***
N(1900)32+****Δ(2300)92+**Λ(2100)72****Σ(1840)32+*Ω(2380)**Ξc(2645)32+***
N(1990)72+**Δ(2350)52*Λ(2110)52+***Σ(1880)12+**Ω(2470)**Ξc(2790)12***
N(2000)52+**Δ(2390)72+*Λ(2325)32*Σ(1900)12*Ξc(2815)32***
N(2040)32+*Δ(2400)92**Λ(2350)92+***Σ(1915)52+****Ξc(2930)*
N(2060)52***Δ(2420)112+****Λ(2585)**Σ(1940)32+*Ξc(2980)***
N(2100)12+***Δ(2750)132**Σ(1940)32***Ξc(3055)***
N(2120)32***Δ(2950)152+**Σ(2000)12*Ξc(3080)***
N(2190)72****Σ(2030)72+****Ξc(3123)*
N(2220)92+****Σ(2070)52+*
N(2250)92****Σ(2080)32+**Ω0
c
12+***
N(2300)12+**Σ(2100)72*Ωc(2770)032+***
N(2570)52**Σ(2250)***Ωc(3000)0***
N(2600)112***Σ(2455)**Ωc(3050)0***
N(2700)132+**Σ(2620)**Ωc(3065)0***
Σ(3000)*Ωc(3090)0***
Ωc(3120)0***
Ξ+
cc
*
Ξ++
cc
***
****Existence is certain, and properties are at least fairly well explored.
***Existence ranges from fairly certain to certain, but further confirmation is desirable, and/or quantum numbers, branching fractions, etc. are not well determined.
**Evidence of existence is only fair.
*Evidence of existence is poor.

See also

References

  1. R. Aaij et al. (2015)
  2. "LHCb experiment discovers a new pentaquark". CERN. 2024-12-04. Retrieved 2025-01-21.
  3. "Observation of a strange pentaquark, a doubly charged tetraquark and its neutral partner" . Retrieved 2025-01-21.
  4. Sample, Ian; editor, science (2015-07-14). "Large Hadron Collider scientists discover new particles: pentaquarks". The Guardian. ISSN   0261-3077 . Retrieved 2025-01-21.{{cite news}}: |last2= has generic name (help)
  5. Griffiths, David J. (2008), Introduction to Elementary Particles (2nd revised ed.), WILEY-VCH, pp. 181–188, ISBN   978-3-527-40601-2
  6. P.A Zyla et al. (2020): Particle summary tables – Baryons
  7. J.G. Körner et al. (1994)
  8. P.A. Zyla et al. (2020): Particle listings –
    p+
  9. P.A. Zyla et al. (2020): Particle listings –
    n0
  10. P.A. Zyla et al. (2020): Particle listings –
    Λ
  11. P.A. Zyla et al. (2020): Particle listings –
    Λ
    c
  12. P.A. Zyla et al. (2020): Particle listings –
    Λ
    b
  13. P.A. Zyla et al. (2020): Particle listings –
    Σ+
  14. P.A. Zyla et al. (2020): Particle listings –
    Σ0
  15. P.A. Zyla et al. (2020): Particle listings –
    Σ
  16. 1 2 3 P.A. Zyla et al. (2020): Particle listings –
    Σ
    c
    (2455)
  17. 1 2 P.A. Zyla et al. (2020): Particle listings –
    Σ
    b
  18. P.A. Zyla et al. (2020): Particle listings –
    Ξ0
  19. P.A. Zyla et al. (2020): Particle listings –
    Ξ
  20. P.A. Zyla et al. (2020): Particle listings –
    Ξ+
    c
  21. P.A. Zyla et al. (2020): Particle listings –
    Ξ0
    c
  22. P.A. Zyla et al. (2020): Particle listings –
    Ξ+
    c
  23. P.A. Zyla et al. (2020): Particle listings –
    Ξ0
    c
  24. P.A. Zyla et al. (2020): Particle listings –
    Ξ++
    cc
  25. 1 2 P.A. Zyla et al. (2020): Particle listings –
    Ξ
    b
  26. P.A. Zyla et al. (2020): Particle listings –
    Ω0
    c
  27. P.A. Zyla et al. (2020): Particle listings –
    Ω
    b
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  29. "2022 CODATA Value: neutron mass in u". The NIST Reference on Constants, Units, and Uncertainty. NIST. May 2024. Retrieved 2024-05-18.
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    Δ
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  32. 1 2 3 P.A. Zyla et al. (2020): Particle listings –
    Σ
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  33. 1 2 3 P.A. Zyla et al. (2020): Particle listings –
    Σ
    c
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  34. 1 2 P.A. Zyla et al. (2020): Particle listings –
    Σ
    b
  35. 1 2 P.A. Zyla et al. (2020): Particle listings –
    Ξ
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  36. 1 2 P.A. Zyla et al. (2020): Particle listings –
    Ξ
    c
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    Ξ0
    b
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  38. P.A. Zyla et al. (2020): Particle listings –
    Ξ0
    b
    (5955)
  39. J. Beringer et al. (2012): Particle listings –
    Ω
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Bibliography

Further reading