List of baryons explained

Baryons are composite particles made of three quarks, as opposed to mesons, which are composite particles made of one quark and one antiquark. 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.

Until a few years ago, it was believed that some experiments showed the existence of pentaquarks – baryons made of four quarks and one antiquark.^{[1] [2]} Prior to 2006 the particle physics community as a whole did not view the existence of pentaquarks as likely.^[3] On 13 July 2015, the LHCb collaboration at CERN reported results consistent with pentaquark states in the decay of bottom lambda baryons (Λ).^[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 =  and J =  configurations with positive parity.

• Baryons composed of one type of quark (uuu, ddd, ...) can exist in J =  configuration, but J =  is forbidden by the Pauli exclusion principle.
• Baryons composed of two types of quarks (uud, uus, ...) can exist in both J =  and J =  configurations.
• Baryons composed of three types of quarks (uds, udc, ...) can exist in both J =  and J =  configurations. Two J =  configurations are possible for these baryons.

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), (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,, 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.^{[5] [6]}

 J^P = ⁺ baryons

J^P = ⁺ baryons

class=unsortable	Particle name ! Symbol	Quark content ! Rest mass (MeV/c^2)		J^P	Q (e)				Mean lifetime (s) ! class=unsortable	Commonly decays to
proton^[7]	,,				^+		0	0	0		unobserved
neutron^[8]	,,				^+	0	0	0	0
lambda^[9]				0	^+	0		0	0
charmed lambda^[10]				0	^+		0		0		see decay modes
bottom lambda^[11]				(0)		0	0	0			see decay modes
sigma^[12]				1	^+			0	0
sigma^[13]				1	^+	0		0	0
sigma^[14]				1	^+			0	0
charmed sigma^[15]	(2455)			1	^+		0		0
charmed sigma	(2455)			1	^+		0		0
charmed sigma	(2455)			1	^+	0	0		0
bottom sigma^[16]				(1)			0	0
bottom sigma			unknown	(1)	(^+)	0	0	0		unknown	unknown
bottom sigma				(1)			0	0
xi^[17]					^(+)	0		0	0
xi^[18]					^(+)			0	0
charmed xi^[19]									0		see decay modes
charmed xi^[20]						0			0		see decay modes
charmed xi prime^[21]									0	unknown
charmed xi prime^[22]						0			0	unknown
double charmed xi^[23]							0		0	unknown	see decay modes
double charmed xi			unknown				0		0	unknown	unknown
						0		0			see decay modes
bottom xi or cascade B								0			see decay modes
bottom xi prime^†			unknown			0		0		unknown	unknown
bottom xi prime^†			unknown					0		unknown	unknown
double bottom xi^†			unknown			0	0	0		unknown	unknown
double bottom xi^†			unknown				0	0		unknown	unknown
charmed bottom xi^†			unknown				0			unknown	unknown
charmed bottom xi^†			unknown			0	0			unknown	unknown
charmed bottom xi prime^†			unknown				0			unknown	unknown
charmed bottom xi prime^†			unknown			0	0			unknown	unknown
charmed omega^[25]				(0)		0			0		see decay modes
bottom omega^[26]				(0)				0
double charmed omega^†			unknown	(0)					0	unknown	unknown
charmed bottom omega^†			unknown	(0)		0				unknown	unknown
charmed bottom omega prime^†			unknown	(0)		0				unknown	unknown
double bottom omega^†			unknown	(0)				0		unknown	unknown
double charmed bottom omega^†			unknown	(0)			0			unknown	unknown
charmed double bottom omega^†			unknown	(0)		0	0			unknown	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 whereas that of the neutron is

^[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 =  is given instead.

^[e] There is a controversial discovery claim, disfavored by other experimental data.^[27]

 J^P = ⁺ baryons

J^P = ⁺ baryons

class=unsortable	Particle name ! Symbol	Quark content ! Rest mass (MeV/c^2)		J^P	Q (e)				Mean lifetime (s) ! class=unsortable	Commonly decays to
delta^[28]	(1232)						0	0	0
delta	(1232)						0	0	0
delta	(1232)					0	0	0	0
delta	(1232)						0	0	0
sigma^[29]	(1385)			1				0	0
sigma	(1385)			1		0		0	0
sigma	(1385)			1				0	0
charmed sigma^[30]	(2520)			1			0		0
charmed sigma	(2520)			1			0		0
charmed sigma	(2520)			1		0	0		0
bottom sigma^[31]				(1)			0	0
bottom sigma			unknown	(1)		0	0	0		unknown	unknown
bottom sigma				(1)			0	0
xi^[32]	(1530)					0		0	0
xi	(1530)							0	0
charmed xi^[33]	(2645)								0
charmed xi	(2645)					0			0
double charmed xi^†			unknown				0		0	unknown	unknown
double charmed xi^†			unknown				0		0	unknown	unknown
bottom xi^[34]						0		0
bottom xi^[35]			± 0.05					0			see decay modes
double bottom xi^†			unknown			0	0	0		unknown	unknown
double bottom xi^†			unknown				0	0		unknown	unknown
charmed bottom xi^†			unknown				0			unknown	unknown
charmed bottom xi^†			unknown			0	0			unknown	unknown
omega^[36]				0	^+			0	0
charmed omega^[37]	(2770)			0		0			0	unknown
bottom omega^†			unknown	(0)				0		unknown	unknown
double charmed omega^†			unknown	(0)					0	unknown	unknown
charmed bottom omega^†			unknown	(0)		0				unknown	unknown
double bottom omega^†			unknown	(0)				0		unknown	unknown
triple charmed omega^†			unknown	(0)			0		0	unknown	unknown
double charmed bottom omega^†			unknown	(0)			0			unknown	unknown
charmed double bottom omega^†			unknown	(0)		0	0			unknown	unknown
triple bottom omega^†			unknown	(0)			0	0		unknown	unknown

^† Particle has not yet been observed.

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

Baryon resonance particles

This table gives the name, quantum numbers (where known), and experimental status of baryons resonances confirmed by the PDG.^[38] Baryon resonance particles 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.^[39] The spin-parity J^P (when known) is given with each particle. For the strongly decaying particles, the J^P values are considered to be part of the names, as is the mass for all resonances.

Baryon resonance particles

Nucleons			Δ particles			Λ particles			Σ particles			Ξ and Ω particles			Charmed particles			Bottom particles
p	^+		Δ(1232)	^+		Λ	^+		Σ^+	^+		Ξ^0	^+			^+			^+
n	^+		Δ(1600)	^+		Λ(1405)	^−		Σ^0	^+		Ξ^−	^+		Λc(2595)^+	^−		Λb(5912)^0	^−
N(1440)	^+		Δ(1620)	^−		Λ(1520)	^−		Σ^−	^+		Ξ(1530)	^+		Λc(2625)^+	^−		Λb(5920)^0	^−
N(1520)	^−		Δ(1700)	^−		Λ(1600)	^+		Σ(1385)	^+		Ξ(1620)			Λc(2765)^+			Σb	^+
N(1535)	^−		Δ(1750)	^+		Λ(1670)	^−		Σ(1480)			Ξ(1690)			Λc(2860)^+	^+			^+
N(1650)	^−		Δ(1900)	^−		Λ(1690)	^−		Σ(1560)			Ξ(1820)	^−		Λc(2880)^+	^+		,	^+
N(1675)	^−		Δ(1905)	^+		Λ(1710)	^+		Σ(1580)	^−		Ξ(1950)			Λc(2940)^+	^−		Ξ'b(5935)^−	^+
N(1680)	^+		Δ(1910)	^+		Λ(1800)	^−		Σ(1620)	^−		Ξ(2030)	≥ ?		Σc(2455)	^+		Ξb(5945)^0	^+
N(1700)	^−		Δ(1920)	^+		Λ(1810)	^+		Σ(1660)	^+		Ξ(2120)			Σc(2520)	^+		Ξb(5955)^−	^+
N(1710)	^+		Δ(1930)	^−		Λ(1820)	^+		Σ(1670)	^−		Ξ(2250)			Σc(2800)				^+
N(1720)	^+		Δ(1940)	^−		Λ(1830)	^−		Σ(1690)			Ξ(2370)						Pc(4380)^+
N(1860)	^+		Δ(1950)	^+		Λ(1890)	^+		Σ(1730)	^+		Ξ(2500)				^+		Pc(4450)^+
N(1875)	^−		Δ(2000)	^+		Λ(2000)			Σ(1750)	^−						^+
N(1880)	^+		Δ(2150)	^−		Λ(2020)	^+		Σ(1770)	^+		Ω^−	^+			^+
N(1895)	^−		Δ(2200)	^−		Λ(2050)	^−		Σ(1775)	^−		Ω(2250)^−				^+
N(1900)	^+		Δ(2300)	^+		Λ(2100)	^−		Σ(1840)	^+		Ω(2380)^−			Ξc(2645)	^+
N(1990)	^+		Δ(2350)	^−		Λ(2110)	^+		Σ(1880)	^+		Ω(2470)^−			Ξc(2790)	^−
N(2000)	^+		Δ(2390)	^+		Λ(2325)	^−		Σ(1900)	^−			Ξc(2815)	^−
N(2040)	^+		Δ(2400)	^−		Λ(2350)	^+		Σ(1915)	^+		Ξc(2930)
N(2060)	^−		Δ(2420)	^+		Λ(2585)			Σ(1940)	^+		Ξc(2980)
N(2100)	^+		Δ(2750)	^−			Σ(1940)	^−		Ξc(3055)
N(2120)	^−		Δ(2950)	^+		Σ(2000)	^−		Ξc(3080)
N(2190)	^−			Σ(2030)	^+		Ξc(3123)
N(2220)	^+		Σ(2070)	^+
N(2250)	^−		Σ(2080)	^+			^+
N(2300)	^+		Σ(2100)	^−		Ωc(2770)^0	^+
N(2570)	^−		Σ(2250)			Ωc(3000)^0
N(2600)	^−		Σ(2455)			Ωc(3050)^0
N(2700)	^+		Σ(2620)			Ωc(3065)^0
	Σ(3000)			Ωc(3090)^0
	Ωc(3120)^0

	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

• Baryons
• Eightfold way (physics)
• List of mesons
• List of particles
• Resonance (particle physics)
• Roper resonance
• Timeline of particle discoveries

References

Bibliography

• R. Aaij et al. (LHCb collaboration) . 2015 . Observation of J/ψp resonances consistent with pentaquark states in Λ→J/ψKp decays . 1507.03414 . 10.1103/PhysRevLett.115.072001 . 26317714 . 115 . 7 . 072001 . . 2015PhRvL.115g2001A . 119204136.
• J. Beringer et al. (Particle Data Group) . 2012 . Review of Particle Physics . . 86 . 1 . 010001 . 2012PhRvD..86a0001B . 10.1103/PhysRevD.86.010001 . free. 10481/34377 . free .
• K. Nakamura et al. (Particle Data Group) . 2010 . Review of Particle Physics . . 37 . 7A . 075021 . 2010JPhG...37g5021N . 10.1088/0954-3899/37/7A/075021 . free. 10481/34593 . free .
• C. Amsler et al. (Particle Data Group) . 2008 . Review of Particle Physics . . 667 . 1 . 1–1340 . 2008PhLB..667....1A . 10.1016/j.physletb.2008.07.018 . 1854/LU-685594 . 227119789 . free.
• Web site: V.M. Abazov et al. (DØ Collaboration) . 2008 . Observation of the doubly strange b baryon . Fermilab-Pub-08/335-E.
• Web site: K. Carter . 2006 . The rise and fall of the pentaquark . . . 2008-05-27 . https://web.archive.org/web/20070708143911/http://www.symmetrymagazine.org/cms/?pid=1000377 . 2007-07-08 . dead.
• W.-M. Yao et al. (Particle Data Group) . 2006 . Review of Particle Physics . . 33 . 1 . 1–1232 . astro-ph/0601168 . 2006JPhG...33....1Y . 10.1088/0954-3899/33/1/001 . free.
• Web site: H. Muir . 2003 . Pentaquark discovery confounds sceptics . . 2008-05-27.
• J.G. Körner . M. Krämer . D. Pirjol . amp . 1994 . Heavy Baryons . . 33 . 787–868 . 10.1016/0146-6410(94)90053-1 . hep-ph/9406359 . 1994PrPNP..33..787K . 118931787.

Further reading

• H. Garcilazo . J. Vijande . A. Valcarce . amp . 2007 . Faddeev study of heavy-baryon spectroscopy . . 34 . 5 . 961–976 . 10.1088/0954-3899/34/5/014 . hep-ph/0703257 . 15445714.
• Web site: S. Robbins . 2006 . Physics Particle Overview – Baryons . . 2008-04-20 . dead . https://web.archive.org/web/20080228011850/http://filer.case.edu/sjr16/advanced/extras_particlephys.html . 2008-02-28.
• D.M. Manley . 2005 . Status of baryon spectroscopy . . 5 . 1 . 230–237 . 10.1088/1742-6596/9/1/043 . 2005JPhCS...9..230M . free.
• Book: S.S.M. Wong . 1998 . Introductory Nuclear Physics . 2nd . . New York (NY) . 978-0-471-23973-4.
• Book: R. Shankar . 1994 . Principles of Quantum Mechanics . 2nd . . New York (NY) . 978-0-306-44790-7.
• E. Wigner . 1937 . On the Consequences of the Symmetry of the Nuclear Hamiltonian on the Spectroscopy of Nuclei . . 51 . 2 . 106–119 . 10.1103/PhysRev.51.106 . 1937PhRv...51..106W.
• M. Gell-Mann . 1964 . A Schematic of Baryons and Mesons . . 8 . 3 . 214–215 . 10.1016/S0031-9163(64)92001-3 . 1964PhL.....8..214G.
• W. Heisenberg . 1932 . Über den Bau der Atomkerne I . . 77 . 1–2 . 1–11 . 10.1007/BF01342433 . 1932ZPhy...77....1H . 186218053 . de.
• W. Heisenberg . 1932 . Über den Bau der Atomkerne II . . 78 . 156–164 . 10.1007/BF01337585. 1932ZPhy...78..156H . 3–4 . 186221789 . de.
• W. Heisenberg . 1932 . Über den Bau der Atomkerne III . . 80 . 587–596 . 10.1007/BF01335696. 1933ZPhy...80..587H . 9–10 . 126422047 . de.

External links

• Particle Data Group – The Review of Particle Physics (2018)
• Georgia State University – HyperPhysics
• Baryons made thinkable, an interactive visualisation allowing physical properties to be compared

Notes and References

1. H. Muir (2003)
2. K. Carter (2003)
3. W.-M. Yao et al. (2006): Particle listings – Positive Theta
4. R. Aaij et al. (2015)
5. P.A Zyla et al. (2020): Particle summary tables – Baryons
6. J.G. Körner et al. (1994)
7. P.A. Zyla et al. (2020): Particle listings –
8. P.A. Zyla et al. (2020): Particle listings –
9. P.A. Zyla et al. (2020): Particle listings –
10. P.A. Zyla et al. (2020): Particle listings –
11. P.A. Zyla et al. (2020): Particle listings –
12. P.A. Zyla et al. (2020): Particle listings –
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27. J. Beringer et al. (2012): Particle listings –
28. P.A. Zyla et al. (2020): Particle listings – (1232)
29. P.A. Zyla et al. (2020): Particle listings – (1385)
30. P.A. Zyla et al. (2020): Particle listings – (2520)
31. P.A. Zyla et al. (2020): Particle listings –
32. P.A. Zyla et al. (2020): Particle listings – (1530)
33. P.A. Zyla et al. (2020): Particle listings – (2645)
34. P.A. Zyla et al. (2020): Particle listings – (5945)
35. P.A. Zyla et al. (2020): Particle listings – (5955)
36. J. Beringer et al. (2012): Particle listings –
37. J. Beringer et al. (2012): Particle listings – (2770)
38. Baryon Summary Table . C. Patrignani et al. (Particle Data Group) . Chin. Phys. C . 40 . 100001 . 2018 . 27 September 2018.
39. Crede. Volker. Roberts. Winston. Progress Toward Understanding Baryon Resonances. Rep. Prog. Phys.. 2013. 76. 7. 10.1088/0034-4885/76/7/076301. 23787948. 1302.7299 . 2013RPPh...76g6301C. 076301. 24922824 .