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 (Λ⁰
_b).^[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]

• Baryons composed of one type of quark (uuu, ddd, ...) can exist in J = 3/2 configuration, but J = 1/2 is forbidden by the Pauli exclusion principle.
• Baryons composed of two types of quarks (uud, uus, ...) can exist in both J = 1/2 and J = 3/2 configurations.
• Baryons composed of three types of quarks (uds, udc, ...) can exist in both J = 1/2 and J = 3/2 configurations. Two J = 1/2 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), 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]

 J^P = 1/2⁺ baryons

Zdroj:https://en.wikipedia.org?pojem=List_of_baryons
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J^P = 1/2⁺ baryons

Particle name	Symbol	Quark content	Rest mass (MeV/c2)	I	JP	Q (e)	S	C	B′	Mean lifetime (s)	Commonly decays to
proton[8]	p , p+ , N+	u u d	938.2720813(58)	1/2	1/2+	+1	0	0	0	stable	unobserved
neutron[9]	n , n0 , N0	u d d	939.5654133(58)	1/2	1/2+	0	0	0	0	(8.794±0.006)×10+2	p+ + e− + ν e
lambda[10]	Λ0	u d s	1115.683±0.006	0	1/2+	0	−1	0	0	(2.632±0.020)×10−10	p+ + π− or n0 + π0
charmed lambda[11]	Λ+ c	u d c	2286.46±0.14	0	1/2+	+1	0	+1	0	(2.024±0.031)×10−13	see 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)×10−12	see Λ0 b decay modes
sigma[13]	Σ+	u u s	1189.37±0.07	1	1/2+	+1	−1	0	0	(8.018±0.026)×10−11	p+ + π0 or n0 + π+
sigma[14]	Σ0	u d s	1192.642±0.024	1	1/2+	0	−1	0	0	(7.4±0.7)×10−20	Λ0 + γ
sigma[15]	Σ−	d d s	1197.449±0.030	1	1/2+	−1	−1	0	0	(1.479±0.011)×10−10	n0 + π−
charmed sigma[16]	Σ++ c(2455)	u u c	2453.97±0.14	1	1/2+	+2	0	+1	0	3.48+0.37 −0.16×10−22	Λ+ c + π+
charmed sigma[16]	Σ+ c(2455)	u d c	2452.9±0.4	1	1/2+	+1	0	+1	0	>1.43×10−22	Λ+ c + π0
charmed sigma[16]	Σ0 c(2455)	d d c	2453.75±0.14	1	1/2+	0	0	+1	0	3.60+0.42 −0.20×10−22	Λ+ c + π−
bottom sigma[17]	Σ+ b	u u b	5810.56±0.25	(1)	(1/2+)	+1	0	0	−1	(1.32±0.13)×10−22	Λ0 b + π+
bottom sigma†	Σ0 b	u d b	unknown	(1)	(1/2+)	0	0	0	−1	unknown	unknown
bottom sigma[17]	Σ− b	d d b	5815.64±0.27	(1)	(1/2+)	−1	0	0	−1	(1.24±0.12)×10−22	Λ0 b + π−
xi[18]	Ξ0	u s s	1314.86±0.20	1/2	1/2(+)	0	−2	0	0	(2.90±0.09)×10−10	Λ0 + π0
xi[19]	Ξ−	d s s	1321.71±0.07	1/2	1/2(+)	−1	−2	0	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	+1	0	(4.56±0.05)×10−13	see Ξ+ c decay modes
charmed xi[21]	Ξ0 c	d s c	2470.90+0.22 −0.29	(1/2)	(1/2+)	0	−1	+1	0	(1.53±0.06)×10−13	see Ξ0 c decay modes
charmed xi prime[22]	Ξ′+ c	u s c	2578.4±0.5	(1/2)	(1/2+)	+1	−1	+1	0	unknown	Ξ+ c + γ (seen)
charmed xi prime[23]	Ξ′0 c	d s c	2579.2±0.5	(1/2)	(1/2+)	0	−1	+1	0	unknown	Ξ0 c + γ (seen)
double charmed xi[24]	Ξ++ cc	u c c	3621.2±0.7	(1/2)	(1/2+)	+2	0	+2	0	unknown	see Ξ++ cc decay modes
double charmed xi	Ξ+ cc	d c c	unknown	(1/2)	(1/2+)	+1	0	+2	0	unknown	unknown
bottom xi[25] or cascade B	Ξ0 b	u s b	5791.9±0.5	(1/2)	(1/2+)	0	−1	0	−1	(1.480±0.030)×10−12	see Ξ0 b decay modes
bottom xi[25] or cascade B	Ξ− b	d s b	5797.0±0.6	(1/2)	(1/2+)	−1	−1	0	−1	(1.572±0.040)×10−12	see Ξ− b decay modes
bottom xi prime†	Ξ′0 b	u s b	unknown	(1/2)	(1/2+)	0	−1	0	−1	unknown	unknown
bottom xi prime†	Ξ′− b	d s b	unknown	(1/2)	(1/2+)	−1	−1	0	−1	unknown	unknown
double bottom xi†	Ξ0 bb	u b b	unknown	(1/2)	(1/2+)	0	0	0	−2	unknown	unknown
double bottom xi†	Ξ− bb	d b b	unknown	(1/2)	(1/2+)	−1	0	0	−2	unknown	unknown
charmed bottom xi†	Ξ+ cb	u c b	unknown	(1/2)	(1/2+)	+1	0	+1	−1	unknown	unknown
charmed bottom xi†	Ξ0 cb	d c b	unknown	(1/2)	(1/2+)	0	0	+1	−1	unknown	unknown