List of baryons

This is a list of known and predicted baryons, which are the family of subatomic particles with a baryon number of 1. The term baryon is usually used to refer to triquarks—baryons made of three quarks. "Exotic" baryons made of four quarks and one anti-quark, known as the pentaquarks, are also listed, but their discovery is not generally accepted. Each baryon has a corresponding antiparticle (anti-baryon) where quarks are replaced by their corresponding antiquarks and vice-versa. For example, a proton is made of two up quarks and one down quark, and the anti-proton is made of two up antiquarks and one down antiquark.

Baryons are a sub-family of the hadrons—particles made of quarks—and as such, participate in the strong interaction.

Overview

Combinations of three u, d or s quarks forming baryons with a spin-3⁄2 form the *baryon decuplet*.

Combinations of three u, d or s quarks forming baryons with a spin-1⁄2 form the *baryon octet*

Baryons are classified into groups according to their isospin (I) values and quark (q) content. There are six groups of triquarks—nucleon (
N
), Delta (
Δ
), Lambda (
Λ
), Sigma (
Σ
), Xi (
Ξ
), and Omega (
Ω
). The rules for classification are defined by the Particle Data Group. These rules consider the up (
u
), down (
d
) and strange (
s
) quarks to be light and the charm (
c
), bottom (
b
), and top (
t
) to be heavy. The rules cover all the particles that can be made from three of each of the six quarks, even though baryons made of t quarks are not expected to exist because of the t quark's short lifetime. The rules do not cover pentaquarks.^[1]

Baryons with three
u
and/or
d
quarks are
N
's (I = 1⁄2) or
Δ
's (I = 3⁄2).
Baryons with two
u
and/or
d
quarks are
Λ
's (I = 0) or
Σ
's (I = 1). If the third quark is heavy, its identity is given by a subscript.
Baryons with one
u
or
d
quark are
Ξ
's (I = 1⁄2). One or two subscripts are used if one or both of the remaining quarks are heavy.
Baryons with no
u
or
d
quarks are
Ω
's (I = 0), and subscripts indicate any heavy quark content.
Baryons that decay strongly have their masses as part of their names. For example, Σ⁰
does not decay strongly, but Δ⁺⁺
(1232) does.
Baryons of same quark content and same isospin, but of higher total angular momentum (J) are indicated by a * in their symbol.^{[citation needed]}
Two baryons can be made of three different quarks in total angular momentum J = 1⁄2 configuration. In this case, a prime (′) is used to distinguish between the two baryons. ^{[citation needed]}

Exception: When two of the three quarks are one up and one down quark, one baryon is dubbed Λ while the other is dubbed Σ.

Quarks carry charge, so knowing the charge of a particle indirectly gives the quark content. For example, the rules above say that the
Σ
_b contains a b and some combination of two u and/or d quarks. A
Σ⁰
_b must be one u quark (Q = 2⁄3), one d quark (Q = −1⁄3), and one b quark (Q = −1⁄3) to have the correct charge (Q = 0).

Lists of baryons

These list details all known and predicted triquark baryons in total angular momentum J = 1⁄2 and J = 3⁄2 configurations, as well as all the reported pentaquarks baryons. Antiparticles are not listed in the tables; however, they simply would have all quarks changed to antiquarks (and antiquarks changed to quarks), and their baryon number (B), charge (Q), strangeness (S), charm (C) and bottomness (B′) quantum numbers would have their signs flipped.

Particles with ^† next to their names have been predicted by the standard model but not yet observed. Isospin (I), total angular momentum (J), and parity (P) values marked with *'s have not been firmly established by experiments, but are predicted by the quark model and are consistent with the measurements.^[2]^[3]

J = 1⁄2 baryons (triquarks)

J = 1⁄2 baryons (triquarks)
Particle	Symbol	Quark content	Rest mass MeV/c²	I	J^P	Q	S	C	B′	Mean lifetime s	Commonly decays to
proton ^[4]	p / p⁺ / N⁺	u u d	938.272 029 ± 0.000 080^[a]	1⁄2	1⁄2⁺	+1	0	0	0	Stable^[b]	Unobserved
neutron ^[5]	n / n⁰ / N⁰	u d d	939.565 360 ± 0.000 081^[a]	1⁄2	1⁄2⁺	0	0	0	0	885.7 ± 0.8^[c]	p⁺ + e⁻ + ν _e
Lambda ^[6]	Λ⁰	u d s	1 115.683 ± 0.006	0	1⁄2⁺	0	−1	0	0	2.631 ± 0.020 × 10⁻¹⁰	p⁺ + π⁻ or n⁰ + π⁰
charmed Lambda ^[7]	Λ⁺ _c	u d c	2 286.46 ± 0.14	0	1⁄2* ⁺	+1	0	+1	0	2.00 ± 0.06 × 10⁻¹³	See Λ⁺ _c Decay Modes
bottom Lambda ^[8]	Λ⁰ _b	u d b	5 620.2 ± 1.6	0*	1⁄2* ^{+^*}	0	0	0	−1	1.409^+0.055 _−0.054 × 10⁻¹²	See Λ⁰ _b Decay Modes
Sigma ^[9]	Σ⁺	u u s	1 189.37 ± 0.07	1	1⁄2⁺	+1	−1	0	0	8.018 ± 0.026 × 10⁻¹¹	p⁺ + π⁰ or n⁰ + π⁺
Sigma ^[10]	Σ⁰	u d s	1 192.642 ± 0.024	1	1⁄2⁺	0	−1	0	0	7.4 ± 0.7 × 10⁻²⁰	Λ⁰ + γ
Sigma ^[11]	Σ⁻	d d s	1 197.449 ± 0.030	1	1⁄2⁺	−1	−1	0	0	1.479 ± 0.011 × 10⁻¹⁰	n⁰ + π⁻
charmed Sigma ^[12]	Σ⁺⁺ _c(2455)	u u c	2 454.02 ± 0.18	1	1⁄2* ^{+^*}	+2	0	+1	0		Λ⁺ _c + π⁺
charmed Sigma ^[12]	Σ⁺ _c(2455)	u d c	2 452.9 ± 0.4	1	1⁄2* ^{+^*}	+1	0	+1	0		Λ⁺ _c + π⁰
charmed Sigma ^[12]	Σ⁰ _c(2455)	d d c	2 453.76 ± 0.18	1	1⁄2* ^{+^*}	0	0	+1	0		Λ⁺ _c + π⁻
bottom Sigma ^[13]	Σ⁺ _b(?^[d])	u u b	5 807.8^+3.7 _−3.9	1*	1⁄2* ^{+^*}	+1	0	0	−1		Λ⁰ _b + π⁺
bottom Sigma^†	Σ⁰ _b(?^[d])	u d b		1*	1⁄2* ^{+^*}	0	0	0	−1
bottom Sigma ^[13]	Σ⁻ _b(?^[d])	d d b	5 815.2 ± 2.7	1*	1⁄2* ^{+^*}	−1	0	0	−1		Λ⁰ _b + π⁻
Xi ^[14]	Ξ⁰	u s s	1 314.86 ± 0.20	1⁄2	1⁄2^{+^*}	0	−2	0	0	2.90 ± 0.09 × 10⁻¹⁰	Λ⁰ + π⁰
Xi ^[15]	Ξ⁻	d s s	1 321.71 ± 0.07	1⁄2	1⁄2^{+^*}	−1	−2	0	0	1.639 ± 0.015 × 10⁻¹⁰	Λ⁰ + π⁻
charmed Xi^[16]	Ξ⁺ _c	u s c	2 467.9 ± 0.4	1⁄2	1⁄2* ^{+^*}	+1	−1	+1	0	4.42 ± 0.26 × 10⁻¹³	See Ξ⁺ _c Decay Modes
charmed Xi^[16]	Ξ⁰ _c	d s c	2 471.0 ± 0.4	1⁄2	1⁄2* ^{+^*}	0	−1	+1	0	1.12^+0.13 × 10⁻¹³	See Ξ⁰ _c Decay Modes
charmed Xi prime^[16]	Ξ′⁺ _c	u s c	2 575.7 ± 3.1	1⁄2	1⁄2* ^{+^*}	+1	−1	+1	0		Ξ⁺ _c+ γ (seen)
charmed Xi prime^[16]	Ξ′⁰ _c	d s c	2 578.0 ± 2.9	1⁄2	1⁄2* ^{+^*}	+1	−1	+1	0		Ξ⁰ _c+ γ (seen)
double charmed Xi^[e]^†	Ξ⁺⁺ _cc	u c c		1⁄2*	1⁄2* ^{+^*}	+2	0	+2	0
double charmed Xi^[e] ^[17]	Ξ⁺ _cc	d c c	3 518.9 ± 0.9^[c]	1⁄2*	1⁄2* ^{+^*}	+1	0	+2	0	<3.3 × 10⁻¹⁴ ^[e]	Λ⁺ _c + K⁻ + π⁺ ^[e] or p⁺ + D⁺ + K⁻ ^[e]
bottom Xi (or Cascade B) ^[18]	Ξ⁰ _b	u s b		1⁄2*	1⁄2* ^{+^*}	0	−1	0	−1	1.42^+0.28 _−0.24 × 10⁻¹² ^[f]	See Ξ _b Decay Modes
bottom Xi (or Cascade B) ^[18]^[19]^[20]	Ξ⁻ _b	d s b	5 792.9 ± 4.2	1⁄2*	1⁄2* ^{+^*}	−1	−1	0	−1	1.42^+0.28 _−0.24 × 10⁻¹² ^[f]	See Ξ _b Decay Modes ( Ξ⁻ + J/ψ was also seen)
bottom Xi prime^†	Ξ′⁰ _b	u s b		0*	1⁄2* ⁺*	0	−1	0	−1
bottom Xi prime^†	Ξ′⁻ _b	d s b		0*	1⁄2* ⁺*	0	−1	0	−1
double bottom Xi^†	Ξ⁰ _bb	u b b		1⁄2*	1⁄2* ^{+^*}	0	0	0	−2
double bottom Xi^†	Ξ⁻ _bb	d b b		1⁄2*	1⁄2* ^{+^*}	−1	0	0	−2
charmed bottom Xi^†	Ξ⁺ _cb	u c b		1⁄2*	1⁄2* ⁺	+1	0	+1	−1
charmed bottom Xi^†	Ξ⁰ _cb	d c b		1⁄2*	1⁄2* ^{+^*}	0	0	+1	−1
charmed bottom Xi prime^†	Ξ′⁺ _cb	u c b		0*	1⁄2* ⁺	+1	0	+1	−1
charmed bottom Xi prime^†	Ξ′⁰ _cb	d c b		0*	1⁄2* ⁺	+1	0	+1	−1
charmed Omega^[21]	Ω⁰ _c	s s c	2 697.5 ± 2.6	0	1⁄2* ^{+^*}	0	−2	+1	0	6.9 ± 1.2 × 10⁻¹⁴	See Ω⁰ _c Decay Modes
bottom Omega^†	Ω⁻ _b	s s b		0*	1⁄2* ^{+^*}	−1	−2	0	−1
double charmed Omega^†	Ω⁺ _cc	s c c		0*	1⁄2* ^{+^*}	+1	−1	+2	0
charmed bottom Omega^†	Ω⁰ _cb	s c b		0*	1⁄2* ^{+^*}	0	−1	+1	−1
charmed bottom Omega prime^†	Ω′⁰ _cb	s c b		0*	1⁄2* ^{+^*}	0	−1	+1	−1
double bottom Omega^†	Ω⁻ _bb	s b b		0*	1⁄2* ^{+^*}	−1	−1	0	−2
double charmed bottom Omega^†	Ω⁺ _ccb	c c b		0*	1⁄2* ^{+^*}	+1	0	+2	−1
charmed double bottom Omega^†	Ω⁰ _cbb	c b b		0*	1⁄2* ^{+^*}	0	0	+1	−2

^[a]The masses of the proton and neutron are known with much better precision in atomic mass units than in Electron volt/c², due to the relatively poorly known value of the elementary charge. In atomic mass unit, the mass of the proton is 1.00727646688(13) u while that of the neutron is 1.00866491560(55) u.
^[b] At least 10³⁵ years. See proton decay.
^[c] For free neutrons; in most common nuclei, neutrons are stable.
^[d] The specific values of the name hasn't been decided yet. Will probably end up to something close to
Σ
_b(5810)
^[e] Some controversy exists about this data. See references
^[f] This is actually a measurement of the average lifetime of b-baryons that decay to a jet containing a same sign
Ξ
^∓
ℓ
^∓ pair. Presumably the mix is mainly
Ξ
_b, with some
Λ
_b.

J = 3⁄2 baryons (triquarks)

J = 3⁄2 baryons (triquarks)
Particle	Symbol	Quark content	Rest mass MeV/c²	Isospin I	Spin(Parity) J^P	Q	S	C	B′	Mean lifetime s	Commonly decays to
Delta ^[22]	Δ⁺⁺ (1232)	u u u	1232 ± 1	3⁄2	3⁄2⁺	+2	0	0	0	6 × 10⁻²⁴ ^[23]	p⁺ + π⁺
Delta ^[22]	Δ⁺ (1232)	u u d	1 232 ± 1	3⁄2	3⁄2⁺	+1	0	0	0	6 × 10⁻²⁴ ^[23]	π⁺ + n⁰ or π⁰ + p⁺
Delta ^[22]	Δ⁰ (1232)	u d d	1 232 ± 1	3⁄2	3⁄2⁺	0	0	0	0	6 × 10⁻²⁴ ^[23]	π⁰ + n⁰ or π⁻ + p⁺
Delta ^[22]	Δ⁻ (1232)	d d d	1 232 ± 1	3⁄2	3⁄2⁺	−1	0	0	0	6 × 10⁻²⁴ ^[23]	π⁻ + n⁰
Sigma ^[24]	Σ^∗+ (1385)	u u s	1 382.8 ± 0.4	1	3⁄2⁺	+1	−1	0	0		Λ⁰ + π⁺ or Σ⁺ + π⁰ or Σ⁰ + π⁺
Sigma ^[24]	Σ^∗0 (1385)	u d s	1 383.7 ± 1.0	1	3⁄2⁺	0	−1	0	0		Λ⁰ + π⁰ or Σ⁺ + π⁻ or Σ⁰ + π⁰
Sigma ^[24]	Σ^∗− (1385)	d d s	1 387.2 ± 0.5	1	3⁄2⁺	−1	−1	0	0		Λ⁰ + π⁻ or Σ⁰ + π⁻ or Σ⁻ + π⁰ or
charmed Sigma ^[25]	Σ^∗++ _c(2520)	u u c	2 518.4 ± 0.6	1	3⁄2* ^{+^*}	+2	0	+1	0		Λ⁺ _c + π⁺
charmed Sigma ^[25]	Σ^∗+ _c(2520)	u d c	2 517.5 ± 2.3	1	3⁄2* ^{+^*}	+1	0	+1	0		Λ⁺ _c + π⁰
charmed Sigma ^[25]	Σ^∗0 _c(2520)	d d c	2 518.0 ± 0.5	1	3⁄2* ^{+^*}	0	0	+1	0		Λ⁺ _c + π⁻
bottom Sigma^†	Σ^∗+ _b	u u b		1*	3⁄2* ^{+^*}	+1	0	0	−1
bottom Sigma^†	Σ^∗0 _b	u d b		1*	3⁄2* ^{+^*}	0	0	0	−1
bottom Sigma^†	Σ^∗− _b	d d b		1*	3⁄2* ^{+^*}	−1	0	0	−1
Xi ^[26]	Ξ^∗0 (1530)	u s s	1 531.80 ± 0.32	1⁄2	3⁄2⁺	0	−2	0	0		Ξ⁰ + π⁰ or Ξ⁻ + π⁺
Xi ^[26]	Ξ^∗− (1530)	d s s	1 535.0 ± 0.6	1⁄2	3⁄2⁺	−1	−2	0	0		Ξ⁰ + π⁻ or Ξ⁻ + π⁰
charmed Xi ^[27]	Ξ^∗+ _c(2645)	u s c	2 646.6 ± 1.4	1⁄2	3⁄2* ^{+^*}	+1	−1	+1	0		Ξ⁺ _c + π⁰ (seen)
charmed Xi ^[27]	Ξ^∗0 _c(2645)	d s c	2 646.1 ± 1.2	1⁄2	3⁄2* ^{+^*}	0	−1	+1	0		Ξ⁺ _c + π⁻ (seen)
double charmed Xi^†	Ξ^∗++ _cc	u c c		1⁄2*	3⁄2* ^{+^*}	+2	0	+2	0
double charmed Xi^†	Ξ^∗+ _cc	d c c		1⁄2*	3⁄2* ^{+^*}	+1	0	+2	0
bottom Xi^†	Ξ^∗0 _b	u s b		1⁄2*	3⁄2* ^{+^*}	0	−1	0	−1
bottom Xi^†	Ξ^∗− _b	d s b		1⁄2*	3⁄2* ^{+^*}	−1	−1	0	−1
double bottom Xi^†	Ξ^∗0 _bb	u b b		1⁄2*	3⁄2* ^{+^*}	0	0	0	−2
double bottom Xi^†	Ξ^∗− _bb	d b b		1⁄2*	3⁄2* ^{+^*}	−1	0	0	−2
charmed bottom Xi^†	Ξ^∗+ _cb	u c b		1⁄2*	3⁄2* ^{+^*}	+1	0	+1	−1
charmed bottom Xi^†	Ξ^∗0 _cb	d c b		1⁄2*	3⁄2* ^{+^*}	0	0	+1	−1
Omega ^[28]	Ω⁻	s s s	1 672.45 ± 0.29	0	3⁄2⁺	−1	−3	0	0	8.21 ± 0.11 × 10⁻¹¹	Λ⁰ + K⁻ or Ξ⁰ + π⁻ or Ξ⁻ + π⁰
charmed Omega ^[29]	Ω^∗0 _c(2770)	s s c	2 768.3 ± 1.5	0	3⁄2* ^{+^*}	0	−2	+1	0		Ω^∗0 _c+ γ
bottom Omega^†	Ω^∗− _b	s s b		0*	3⁄2* ^{+^*}	−1	−2	0	−1
double charmed Omega^†	Ω^∗+ _cc	s c c		0*	3⁄2* ^{+^*}	+1	−1	+2	0
charmed bottom Omega^†	Ω^∗0 _cb	s c b		0*	3⁄2* ^{+^*}	0	−1	+1	−1
double bottom Omega^†	Ω^∗− _bb	s b b		0*	3⁄2* ^{+^*}	−1	−1	0	−2
triple charmed Omega^†	Ω⁺⁺ _ccc	c c c		0*	3⁄2* ^{+^*}	+2	0	+3	0
double charmed bottom Omega^†	Ω^∗+ _ccb	c c b		0*	3⁄2* ^{+^*}	+1	0	+2	−1
charmed double bottom Omega^†	Ω^∗0 _cbb	c b b		0*	3⁄2* ^{+^*}	0	0	+1	−2
triple bottom Omega^†	Ω⁻ _bbb	b b b		0	3⁄2* ^{+^*}	−1	0	0	−3

Exotic baryons (pentaquarks)

This lists details pentaquarks reported to exist. However, other groups have looked for them and reported to have found nothing. Data is controversial to the point that the existence of pentaquarks is not generally accepted.

Exotic baryons (pentaquarks)
Particle	Symbol	Quark content	Rest mass MeV/c²	I	J^P	Q	S	C	Commonly decays to
Theta ^[30]	Θ⁺ (1540)	u u d d s	1 533.6 ± 2.4	0	?^?	+1	+1	0	K⁰ + p⁺ or K⁺ + n⁰
Charmed Theta ^[31]	Θ⁰ _c (3100)	u u d d c	3 099 ± 8	0	?^?	0	0	−1
Phi ^[32]	Φ⁰ (1860)	s s d d u	1 862 ± 2	3⁄2	?^?	0	−2	0

References

^ Yao et al. (2006): Naming scheme for hadrons
^ Yao et al. (2006): Particle summary tables - Baryon
^ Körner et al. (1994)
^ Yao et al. (2006): Particle listings - Proton
^ Yao et al. (2006): Particle listings - Neutron
^ Yao et al. (2006): Particle listings - Lambda
^ Yao et al. (2006): Particle listings - Charmed Lambda
^ Yao et al. (2006): Particle listings - Bottom Lambda
^ Yao et al. (2006): Particle listings - Positive Sigma
^ Yao et al. (2006): Particle listings - Neutral Sigma
^ Yao et al. (2006): Particle listings - Negative Sigma
^ ^a ^b ^c Yao et al. (2006): Particle listings - Charmed Sigma(2455)
^ ^a ^b Aaltonen et al. (2007a)
^ Yao et al. (2006): Particle listings - Neutral Xi
^ Yao et al. (2006): Particle listings - Negative Xi
^ ^a ^b ^c ^d Yao et al. (2006): Particle listings - Charmed baryons
^ Yao et al. (2006): Particle listings - Double charmed positive Xi
^ ^a ^b Yao et al. (2006): Particle listings - Bottom Xis
^ Abazov et al. (2007)
^ Aaltonen et al. (2007b)
^ Yao et al. (2006): Particle listings - Charmed Omega
^ ^a ^b ^c ^d Yao et al. (2006): Particle listings - Delta(1232)
^ ^a ^b ^c ^d "Physics Particle Overview — Baryons". Retrieved 2008-04-20.
^ ^a ^b ^c Yao et al. (2006): Particle listings - Sigma(1385)
^ ^a ^b ^c Yao et al. (2006): Particle listings - Charmed Sigma(2520)
^ ^a ^b Yao et al. (2006): Particle listings - Xi(1530)
^ ^a ^b Yao et al. (2006): Particle listings - Charmed Xi(2645)
^ Yao et al. (2006): Particle listings - Negative Omega
^ Yao et al. (2006): Particle listings - Neutral Charmed Omega(2770)
^ Yao et al. (2006): Particle listings - Positive Theta
^ Yao et al. (2006): Particle listings - Charmed Theta
^ Yao et al. (2006): Particle listings - Phi(1860)

Bibliography

T. Aaltonen; et al. (2007a). "First Observation of Heavy Baryons
Σ
_b and
Σ^∗
_b". Physical Review Letters. 99. CDF Collaboration: 202001. doi:10.1103/PhysRevLett.99.202001. arXiv:0706.3868. {{cite journal}}: Explicit use of et al. in: |author= (help)
T. Aaltonen; et al. (2007b). "Observation and mass measurement of the baryon
Ξ⁻
_b". Physical Review Letters. 99: 052002. arXiv:0707.0589. {{cite journal}}: Explicit use of et al. in: |author= (help)
V. M. Abazov; et al. (2007). "Direct observation of the strange b baryon Xi(b)-". Physical Review Letters. 99: 052001. arXiv:0706.1690. {{cite journal}}: Explicit use of et al. in: |author= (help)
J. G. Körner, M. Krämer, and D. Pirjol (1994). "Heavy Baryons". Progress in Particle and Nuclear Physics. 33: 787–868. arXiv:hep-ph/9406359.{{cite journal}}: CS1 maint: multiple names: authors list (link)
W.-M. Yao; et al. (2006). "Review of Particle Physics". Journal of Physics G. 33. Particle Data Group: 1–1232. doi:10.1088/0954-3899/33/1/001. {{cite journal}}: Explicit use of et al. in: |author= (help)