Baryons
n |
p |
Σ− |
Σ0 |
Σ+ |
Ξ− |
Ξ0 |
Σ0 c |
Σ+ c |
Σ++ c |
Ξ0 c |
Ξ+ c |
Ω0 c |
Ξ+ cc |
Ξ++ cc |
Ω+ cc |
Σ− b |
Σ0 b |
Σ+ b |
Ξ− b |
Ξ0 b |
Ω− b |
Ξ− bb |
Ξ0 bb |
Ω− bb |
Ξ0 cb |
Ξ+ cb |
Ω0 cb |
Ω+ ccb |
Ω0 cbb |
spin-1/2 baryons |
more spin-1/2 baryons |
spin-3/2 baryons |
quarks in baryons |
spin-1/2 anti- baryons |
more spin-1/2 anti- baryons |
spin-3/2 anti- baryons |
anti- quarks in anti- baryons |
mass |
spin |
baryon number |
charge |
isospin |
strangeness |
charm |
bottomness |
topness |
what's the pattern? |
why a triangle? |
why a tetrahedron? |
why a hypertetrahedron? |
what's missing? |
what's the significance of spin? |
Notes
This representation of 150 baryons and antibaryons shows neutrons, protons and some of their weirder cousins
Baryons are particles made up of three quarks (or, in the case of antibaryons, three antiquarks). The most common baryons are the neutron and the proton, which combine to form the nuclei of atoms.
The baryons and antibaryons shown represent every possible combination of down, up, strange, charm and bottom quarks and antiquarks. Baryons and antibaryons that contain top quarks and antiquarks are not shown, because these have such high mass that it is difficult to create them in particle accelerators.
Every inch of this visualization is active. Move your mouse over a baryon or antibaryon to show its name, properties and further information. Move your mouse over a page tab to show more baryons and antibaryons, or which quarks and antiquarks comprise each one. Or move your mouse over a property to show the value of that property for each of the baryons and antibaryons. Click on a control to hold it down, then click elsewhere to release it.
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More
This is one of a series of visualizations of what things are made of, from elementary particles to organic molecules…
Baryons – this page
…check back soon for the next in the series
Latest things made thinkable
Sources
Introductory Nuclear Physics by Kenneth S. Krane
Text
A text summary of this presentation is shown below for easy reference
Particles
up quark
charm quark
top quark
up antiquark
charm antiquark
top antiquark
down quark
strange quark
bottom quark
down antiquark
strange antiquark
bottom antiquark
neutron n
neutrons are the uncharged particles in the nuclei of atoms; because they are uncharged, the number of neutrons does not affect the number of electrons bound to the nucleus, so does not change the chemical properties of the atom; it does, however, affect the mass of the atom slightly; a neutron consists of an up quark and two down quarks (u, d and d)
proton p
protons are the positively-charged particles in the nuclei of all atoms; their positive charge binds an equal number of negatively-charged electrons to the nucleus, giving the atom its chemical properties; a proton consists of two up quarks and a down quark (u, u and d)
Sigma Σ−
this Sigma baryon consists of two down quarks and a strange quark (d, d and s)
Sigma Σ0
this Sigma baryon consists of an up quark, a down quark and a strange quark (u, d and s)
Sigma Σ+
this Sigma baryon consists of two up quarks and a strange quark (u, u and s)
Xi Ξ−
this Xi baryon consists of a down quark and two strange quarks (d, s and s)
Xi Ξ0
this Xi baryon consists of an up quark and two strange quarks (u, s and s)
charmed Sigma Σ0
c
this charmed Sigma baryon consists of two down quarks and a charm quark (d, d and c)
charmed Sigma Σ+
c
this charmed Sigma baryon consists of an up quark, a down quark and a charm quark (u, d and c)
charmed Sigma Σ++
c
this charmed Sigma baryon consists of two up quarks and a charm quark (u, u and c)
charmed Xi Ξ0
c
this charmed Xi baryon consists of a down quark, a strange quark and a charm quark (d, s and c)
charmed Xi Ξ+
c
this charmed Xi baryon consists of an up quark, a strange quark and a charm quark (u, s and c)
charmed Omega Ω0
c
this charmed Omega baryon consists of two strange quarks and a charm quark (s, s and c)
double charmed Xi Ξ+
cc
this double charmed Xi baryon consists of a down quark and two charm quarks (d, c and c)
double charmed Xi Ξ++
cc
this double charmed Xi baryon consists of an up quark and two charm quarks (u, c and c)
double charmed Omega Ω+
cc
this double charmed Omega baryon consists of a strange quark and two charm quarks (s, c and c)
bottom Sigma Σ−
b
this bottom Sigma baryon consists of two down quarks and a bottom quark (d, d and b)
bottom Sigma Σ0
b
this bottom Sigma baryon consists of an up quark, a down quark and a bottom quark (u, d and b)
bottom Sigma Σ+
b
this bottom Sigma baryon consists of two up quarks and a bottom quark (u, u and b)
bottom Xi Ξ−
b
this bottom Xi baryon consists of a down quark, a strange quark and a bottom quark (d, s and b)
bottom Xi Ξ0
b
this bottom Xi baryon consists of an up quark, a strange quark and a bottom quark (u, s and b)
bottom Omega Ω−
b
this bottom Omega baryon consists of two strange quarks and a bottom quark (s, s and b)
double bottom Xi Ξ−
bb
this double bottom Xi baryon consists of a down quark and two bottom quarks (d, b and b)
double bottom Xi Ξ0
bb
this double bottom Xi baryon consists of an up quark and two bottom quarks (u, b and b)
double bottom Omega Ω−
bb
this double bottom Omega baryon consists of a strange quark and two bottom quarks (s, b and b)
charmed bottom Xi Ξ0
cb
this charmed bottom Xi baryon consists of a down quark, a charm quark and a bottom quark (d, c and b)
charmed bottom Xi Ξ+
cb
this charmed bottom Xi baryon consists of an up quark, a charm quark and a bottom quark (u, c and b)
charmed bottom Omega Ω0
cb
this charmed bottom Omega baryon consists of a strange quark, a charm quark and a bottom quark (s, c and b)
double charmed bottom Omega Ω+
ccb
this double charmed bottom Omega baryon consists of two charm quarks and a bottom quark (c, c and b)
charmed double bottom Omega Ω0
cbb
this charmed double bottom Omega baryon consists of a charm quark and two bottom quarks (c, b and b)
Lambda Λ0
this Lambda baryon consists of an up quark, a down quark and a strange quark (u, d and s)
charmed Lambda Λ+
c
this charmed Lambda baryon consists of an up quark, a down quark and a charm quark (u, d and c)
charmed Xi prime Ξ′0
c
this charmed Xi prime baryon consists of a down quark, a strange quark and a charm quark (d, s and c)
charmed Xi prime Ξ′+
c
this charmed Xi prime baryon consists of an up quark, a strange quark and a charm quark (u, s and c)
bottom Lambda Λ0
b
this bottom Lambda baryon consists of an up quark, a down quark and a bottom quark (u, d and b)
bottom Xi prime Ξ′−
b
this bottom Xi prime baryon consists of a down quark, a strange quark and a bottom quark (d, s and b)
bottom Xi prime Ξ′0
b
this bottom Xi prime baryon consists of an up quark, a strange quark and a bottom quark (u, s and b)
charmed bottom Xi prime Ξ′0
cb
this charmed bottom Xi prime baryon consists of a down quark, a charm quark and a bottom quark (d, c and b)
charmed bottom Xi prime Ξ′+
cb
this charmed bottom Xi prime baryon consists of an up quark, a charm quark and a bottom quark (u, c and b)
charmed bottom Omega prime Ω′0
cb
this charmed bottom Omega prime baryon consists of a strange quark, a charm quark and a bottom quark (s, c and b)
Delta Δ−
this Delta baryon consists of three down quarks (d, d and d)
Delta Δ0
this Delta baryon consists of an up quark and two down quarks (u, d and d)
Delta Δ+
this Delta baryon consists of two up quarks and a down quark (u, u and d)
Delta Δ++
this Delta baryon consists of three up quarks (u, u and u)
Sigma Σ∗−
this Sigma baryon consists of two down quarks and a strange quark (d, d and s)
Sigma Σ∗0
this Sigma baryon consists of an up quark, a down quark and a strange quark (u, d and s)
Sigma Σ∗+
this Sigma baryon consists of two up quarks and a strange quark (u, u and s)
Xi Ξ∗−
this Xi baryon consists of a down quark and two strange quarks (d, s and s)
Xi Ξ∗0
this Xi baryon consists of an up quark and two strange quarks (u, s and s)
Omega Ω−
this Omega baryon consists of three strange quarks (s, s and s)
charmed Sigma Σ∗0
c
this charmed Sigma baryon consists of two down quarks and a charm quark (d, d and c)
charmed Sigma Σ∗+
c
this charmed Sigma baryon consists of an up quark, a down quark and a charm quark (u, d and c)
charmed Sigma Σ∗++
c
this charmed Sigma baryon consists of two up quarks and a charm quark (u, u and c)
charmed Xi Ξ∗0
c
this charmed Xi baryon consists of a down quark, a strange quark and a charm quark (d, s and c)
charmed Xi Ξ∗+
c
this charmed Xi baryon consists of an up quark, a strange quark and a charm quark (u, s and c)
charmed Omega Ω∗0
c
this charmed Omega baryon consists of two strange quarks and a charm quark (s, s and c)
double charmed Xi Ξ∗+
cc
this double charmed Xi baryon consists of a down quark and two charm quarks (d, c and c)
double charmed Xi Ξ∗++
cc
this double charmed Xi baryon consists of an up quark and two charm quarks (u, c and c)
double charmed Omega Ω∗+
cc
this double charmed Omega baryon consists of a strange quark and two charm quarks (s, c and c)
triple charmed Omega Ω++
ccc
this triple charmed Omega baryon consists of three charm quarks (c, c and c)
bottom Sigma Σ∗−
b
this bottom Sigma baryon consists of two down quarks and a bottom quark (d, d and b)
bottom Sigma Σ∗0
b
this bottom Sigma baryon consists of an up quark, a down quark and a bottom quark (u, d and b)
bottom Sigma Σ∗+
b
this bottom Sigma baryon consists of two up quarks and a bottom quark (u, u and b)
bottom Xi Ξ∗−
b
this bottom Xi baryon consists of a down quark, a strange quark and a bottom quark (d, s and b)
bottom Xi Ξ∗0
b
this bottom Xi baryon consists of an up quark, a strange quark and a bottom quark (u, s and b)
bottom Omega Ω∗−
b
this bottom Omega baryon consists of two strange quarks and a bottom quark (s, s and b)
double bottom Xi Ξ∗−
bb
this double bottom Xi baryon consists of a down quark and two bottom quarks (d, b and b)
double bottom Xi Ξ∗0
bb
this double bottom Xi baryon consists of an up quark and two bottom quarks (u, b and b)
double bottom Omega Ω∗−
bb
this double bottom Omega baryon consists of a strange quark and two bottom quarks (s, b and b)
triple bottom Omega Ω−
bbb
this triple bottom Omega baryon consists of three bottom quarks (b, b and b)
charmed bottom Xi Ξ∗0
cb
this charmed bottom Xi baryon consists of a down quark, a charm quark and a bottom quark (d, c and b)
charmed bottom Xi Ξ∗+
cb
this charmed bottom Xi baryon consists of an up quark, a charm quark and a bottom quark (u, c and b)
charmed bottom Omega Ω∗0
cb
this charmed bottom Omega baryon consists of a strange quark, a charm quark and a bottom quark (s, c and b)
double charmed bottom Omega Ω∗+
ccb
this double charmed bottom Omega baryon consists of two charm quarks and a bottom quark (c, c and b)
charmed double bottom Omega Ω∗0
cbb
this charmed double bottom Omega baryon consists of a charm quark and two bottom quarks (c, b and b)
anti-neutron n
neutrons are the uncharged particles in the nuclei of atoms; because they are uncharged, the number of neutrons does not affect the number of electrons bound to the nucleus, so does not change the chemical properties of the atom; it does, however, affect the mass of the atom slightly; an anti-neutron consists of an up antiquark and two down antiquarks (u, d and d)
anti-proton p
protons are the positively-charged particles in the nuclei of all atoms; their positive charge binds an equal number of negatively-charged electrons to the nucleus, giving the atom its chemical properties; an anti-proton consists of two up antiquarks and a down antiquark (u, u and d)
anti-Sigma Σ+
this anti-Sigma baryon consists of two down antiquarks and a strange antiquark (d, d and s)
anti-Sigma Σ0
this anti-Sigma baryon consists of an up antiquark, a down antiquark and a strange antiquark (u, d and s)
anti-Sigma Σ−
this anti-Sigma baryon consists of two up antiquarks and a strange antiquark (u, u and s)
anti-Xi Ξ+
this anti-Xi baryon consists of a down antiquark and two strange antiquarks (d, s and s)
anti-Xi Ξ0
this anti-Xi baryon consists of an up antiquark and two strange antiquarks (u, s and s)
charmed anti-Sigma Σ0
c
this charmed anti-Sigma baryon consists of two down antiquarks and a charm antiquark (d, d and c)
charmed anti-Sigma Σ−
c
this charmed anti-Sigma baryon consists of an up antiquark, a down antiquark and a charm antiquark (u, d and c)
charmed anti-Sigma Σ−−
c
this charmed anti-Sigma baryon consists of two up antiquarks and a charm antiquark (u, u and c)
charmed anti-Xi Ξ0
c
this charmed anti-Xi baryon consists of a down antiquark, a strange antiquark and a charm antiquark (d, s and c)
charmed anti-Xi Ξ−
c
this charmed anti-Xi baryon consists of an up antiquark, a strange antiquark and a charm antiquark (u, s and c)
charmed anti-Omega Ω0
c
this charmed anti-Omega baryon consists of two strange antiquarks and a charm antiquark (s, s and c)
double charmed anti-Xi Ξ−
cc
this double charmed anti-Xi baryon consists of a down antiquark and two charm antiquarks (d, c and c)
double charmed anti-Xi Ξ−−
cc
this double charmed anti-Xi baryon consists of an up antiquark and two charm antiquarks (u, c and c)
double charmed anti-Omega Ω−
cc
this double charmed anti-Omega baryon consists of a strange antiquark and two charm antiquarks (s, c and c)
bottom anti-Sigma Σ+
b
this bottom anti-Sigma baryon consists of two down antiquarks and a bottom antiquark (d, d and b)
bottom anti-Sigma Σ0
b
this bottom anti-Sigma baryon consists of an up antiquark, a down antiquark and a bottom antiquark (u, d and b)
bottom anti-Sigma Σ−
b
this bottom anti-Sigma baryon consists of two up antiquarks and a bottom antiquark (u, u and b)
bottom anti-Xi Ξ+
b
this bottom anti-Xi baryon consists of a down antiquark, a strange antiquark and a bottom antiquark (d, s and b)
bottom anti-Xi Ξ0
b
this bottom anti-Xi baryon consists of an up antiquark, a strange antiquark and a bottom antiquark (u, s and b)
bottom anti-Omega Ω+
b
this bottom anti-Omega baryon consists of two strange antiquarks and a bottom antiquark (s, s and b)
double bottom anti-Xi Ξ+
bb
this double bottom anti-Xi baryon consists of a down antiquark and two bottom antiquarks (d, b and b)
double bottom anti-Xi Ξ0
bb
this double bottom anti-Xi baryon consists of an up antiquark and two bottom antiquarks (u, b and b)
double bottom anti-Omega Ω+
bb
this double bottom anti-Omega baryon consists of a strange antiquark and two bottom antiquarks (s, b and b)
charmed bottom anti-Xi Ξ0
cb
this charmed bottom anti-Xi baryon consists of a down antiquark, a charm antiquark and a bottom antiquark (d, c and b)
charmed bottom anti-Xi Ξ−
cb
this charmed bottom anti-Xi baryon consists of an up antiquark, a charm antiquark and a bottom antiquark (u, c and b)
charmed bottom anti-Omega Ω0
cb
this charmed bottom anti-Omega baryon consists of a strange antiquark, a charm antiquark and a bottom antiquark (s, c and b)
double charmed bottom anti-Omega Ω−
ccb
this double charmed bottom anti-Omega baryon consists of two charm antiquarks and a bottom antiquark (c, c and b)
charmed double bottom anti-Omega Ω0
cbb
this charmed double bottom anti-Omega baryon consists of a charm antiquark and two bottom antiquarks (c, b and b)
anti-Lambda Λ0
this anti-Lambda baryon consists of an up antiquark, a down antiquark and a strange antiquark (u, d and s)
charmed anti-Lambda Λ−
c
this charmed anti-Lambda baryon consists of an up antiquark, a down antiquark and a charm antiquark (u, d and c)
charmed anti-Xi prime Ξ′0
c
this charmed anti-Xi prime baryon consists of a down antiquark, a strange antiquark and a charm antiquark (d, s and c)
charmed anti-Xi prime Ξ′−
c
this charmed anti-Xi prime baryon consists of an up antiquark, a strange antiquark and a charm antiquark (u, s and c)
bottom anti-Lambda Λ0
b
this bottom anti-Lambda baryon consists of an up antiquark, a down antiquark and a bottom antiquark (u, d and b)
bottom anti-Xi prime Ξ′+
b
this bottom anti-Xi prime baryon consists of a down antiquark, a strange antiquark and a bottom antiquark (d, s and b)
bottom anti-Xi prime Ξ′0
b
this bottom anti-Xi prime baryon consists of an up antiquark, a strange antiquark and a bottom antiquark (u, s and b)
charmed bottom anti-Xi prime Ξ′0
cb
this charmed bottom anti-Xi prime baryon consists of a down antiquark, a charm antiquark and a bottom antiquark (d, c and b)
charmed bottom anti-Xi prime Ξ′−
cb
this charmed bottom anti-Xi prime baryon consists of an up antiquark, a charm antiquark and a bottom antiquark (u, c and b)
charmed bottom anti-Omega prime Ω′0
cb
this charmed bottom anti-Omega prime baryon consists of a strange antiquark, a charm antiquark and a bottom antiquark (s, c and b)
anti-Delta Δ+
this anti-Delta baryon consists of three down antiquarks (d, d and d)
anti-Delta Δ0
this anti-Delta baryon consists of an up antiquark and two down antiquarks (u, d and d)
anti-Delta Δ−
this anti-Delta baryon consists of two up antiquarks and a down antiquark (u, u and d)
anti-Delta Δ−−
this anti-Delta baryon consists of three up antiquarks (u, u and u)
anti-Sigma Σ∗+
this anti-Sigma baryon consists of two down antiquarks and a strange antiquark (d, d and s)
anti-Sigma Σ∗0
this anti-Sigma baryon consists of an up antiquark, a down antiquark and a strange antiquark (u, d and s)
anti-Sigma Σ∗−
this anti-Sigma baryon consists of two up antiquarks and a strange antiquark (u, u and s)
anti-Xi Ξ∗+
this anti-Xi baryon consists of a down antiquark and two strange antiquarks (d, s and s)
anti-Xi Ξ∗0
this anti-Xi baryon consists of an up antiquark and two strange antiquarks (u, s and s)
anti-Omega Ω+
this anti-Omega baryon consists of three strange antiquarks (s, s and s)
charmed anti-Sigma Σ∗0
c
this charmed anti-Sigma baryon consists of two down antiquarks and a charm antiquark (d, d and c)
charmed anti-Sigma Σ∗−
c
this charmed anti-Sigma baryon consists of an up antiquark, a down antiquark and a charm antiquark (u, d and c)
charmed anti-Sigma Σ∗−−
c
this charmed anti-Sigma baryon consists of two up antiquarks and a charm antiquark (u, u and c)
charmed anti-Xi Ξ∗0
c
this charmed anti-Xi baryon consists of a down antiquark, a strange antiquark and a charm antiquark (d, s and c)
charmed anti-Xi Ξ∗−
c
this charmed anti-Xi baryon consists of an up antiquark, a strange antiquark and a charm antiquark (u, s and c)
charmed anti-Omega Ω∗0
c
this charmed anti-Omega baryon consists of two strange antiquarks and a charm antiquark (s, s and c)
double charmed anti-Xi Ξ∗−
cc
this double charmed anti-Xi baryon consists of a down antiquark and two charm antiquarks (d, c and c)
double charmed anti-Xi Ξ∗−−
cc
this double charmed anti-Xi baryon consists of an up antiquark and two charm antiquarks (u, c and c)
double charmed anti-Omega Ω∗−
cc
this double charmed anti-Omega baryon consists of a strange antiquark and two charm antiquarks (s, c and c)
triple charmed anti-Omega Ω−−
ccc
this triple charmed anti-Omega baryon consists of three charm antiquarks (c, c and c)
bottom anti-Sigma Σ∗+
b
this bottom anti-Sigma baryon consists of two down antiquarks and a bottom antiquark (d, d and b)
bottom anti-Sigma Σ∗0
b
this bottom anti-Sigma baryon consists of an up antiquark, a down antiquark and a bottom antiquark (u, d and b)
bottom anti-Sigma Σ∗−
b
this bottom anti-Sigma baryon consists of two up antiquarks and a bottom antiquark (u, u and b)
bottom anti-Xi Ξ∗+
b
this bottom anti-Xi baryon consists of a down antiquark, a strange antiquark and a bottom antiquark (d, s and b)
bottom anti-Xi Ξ∗0
b
this bottom anti-Xi baryon consists of an up antiquark, a strange antiquark and a bottom antiquark (u, s and b)
bottom anti-Omega Ω∗+
b
this bottom anti-Omega baryon consists of two strange antiquarks and a bottom antiquark (s, s and b)
double bottom anti-Xi Ξ∗+
bb
this double bottom anti-Xi baryon consists of a down antiquark and two bottom antiquarks (d, b and b)
double bottom anti-Xi Ξ∗0
bb
this double bottom anti-Xi baryon consists of an up antiquark and two bottom antiquarks (u, b and b)
double bottom anti-Omega Ω∗+
bb
this double bottom anti-Omega baryon consists of a strange antiquark and two bottom antiquarks (s, b and b)
triple bottom anti-Omega Ω+
bbb
this triple bottom anti-Omega baryon consists of three bottom antiquarks (b, b and b)
charmed bottom anti-Xi Ξ∗0
cb
this charmed bottom anti-Xi baryon consists of a down antiquark, a charm antiquark and a bottom antiquark (d, c and b)
charmed bottom anti-Xi Ξ∗−
cb
this charmed bottom anti-Xi baryon consists of an up antiquark, a charm antiquark and a bottom antiquark (u, c and b)
charmed bottom anti-Omega Ω∗0
cb
this charmed bottom anti-Omega baryon consists of a strange antiquark, a charm antiquark and a bottom antiquark (s, c and b)
double charmed bottom anti-Omega Ω∗−
ccb
this double charmed bottom anti-Omega baryon consists of two charm antiquarks and a bottom antiquark (c, c and b)
charmed double bottom anti-Omega Ω∗0
cbb
this charmed double bottom anti-Omega baryon consists of a charm antiquark and two bottom antiquarks (c, b and b)
Information
what's the pattern?
the baryons are arranged in a 2-dimensional representation of a 4-dimensional tetra-hedron, i.e. a hypertetrahedron; this is because a baryon is made up of 3 quarks, each of which can be any of the 6 flavours of quark: d, u, s, c, b & t
why a triangle?
with the quarks in baryons tab clicked, look at the top-left group of 10 quark combinations; they form a triangle with ddd in the top-left corner, uuu in the top-right corner, sss in the bottom corner, and every other possible combination of d, u & s quarks in between; these 10 combinations give 18 baryons of different spins and isospins
why a tetrahedron?
now, with the quarks in baryons tab still clicked, imagine the 3 groups of 6, 3 & 1 quark combinations to the right stacked up on top of the triangle of 10 quark combinations in the 3rd dimension; this would form a tetrahedron with ccc in the top corner in the 3rd dimension; this tetrahedron covers all 20 possible combinations of d, u, s & c quarks, giving 40 baryons of different spins and isospins
why a hypertetrahedron?
finally, with the quarks in baryons tab still clicked, imagine, if you can, the remaining groups of 6, 3, 3, 1, 1 & 1 quark combinations below stacked up on top of the tetrahedron of 20 quark combinations in the 4th dimension; this would form a hypertetrahedron with bbb in the top corner in the 4th dimension; this hypertetrahedron covers all 35 possible combinations of d, u, s, c & b quarks, giving 75 baryons of different spins and isospins
what's missing?
baryons and antibaryons that contain top quarks and antiquarks are not shown, because these have such a high mass that it is difficult to create them in particle accelerators; if these massive baryons were shown, they would complete a 5-dimensional tetrahedron covering all 56 possible combinations of 3 quarks, giving 126 baryons of different spins and isospins; throw in the antibaryons, and there is a total of 252 possible baryons and antibaryons
what's the significance of spin?
all baryons have half-integer spin (spin 1/2 or spin 3/2); in other words, all baryons are fermions, subject to the exclusion principle, which means that there is a limit to the number of baryons you can squeeze into a small space; this is what keeps protons and neutrons apart in the nuclei of atoms, and prevents neutron stars from collapsing any further than they already have
Date
First published 31 March 2011