List of particles in matter including fermions and bosons
This is a list of known and hypothesized particles.
Standard Model elementary particles
[
edit
]
See
Standard Model
for the current consensus theory of these particles.
Elementary particles are particles with no measurable internal structure; that is, it is unknown whether they are composed of other particles.
[1]
They are the fundamental objects of
quantum field theory
. Many families and sub-families of elementary particles exist. Elementary particles are classified according to their
spin
.
Fermions
have half-integer spin while
bosons
have integer spin. All the particles of the
Standard Model
have been experimentally observed, including the
Higgs boson
in 2012.
[2]
[3]
Many other hypothetical elementary particles, such as the
graviton
, have been proposed, but not observed experimentally.
Fermions
[
edit
]
Fermions
are one of the two fundamental classes of particles, the other being
bosons
. Fermion particles are described by
Fermi?Dirac statistics
and have
quantum numbers
described by the
Pauli exclusion principle
. They include the
quarks
and
leptons
, as well as any
composite particles
consisting of an odd number of these, such as all
baryons
and many atoms and nuclei.
Fermions have half-integer spin; for all known elementary fermions this is
1
⁄
2
. All known fermions except
neutrinos
, are also
Dirac fermions
; that is, each known fermion has its own distinct
antiparticle
. It is not known whether the
neutrino
is a
Dirac fermion
or a
Majorana fermion
.
[4]
Fermions are the basic building blocks of all
matter
. They are classified according to whether they interact via the
strong interaction
or not. In the Standard Model, there are 12 types of elementary fermions: six
quarks
and six
leptons
.
Quarks
[
edit
]
Quarks
are the fundamental constituents of
hadrons
and interact via the
strong force
. Quarks are the only known carriers of
fractional charge
, but because they combine in groups of three quarks (baryons) or in pairs of one quark and one
antiquark
(mesons), only integer charge is observed in nature. Their respective
antiparticles
are the
antiquarks
, which are identical except that they carry the opposite electric charge (for example the up quark carries charge +
2
⁄
3
, while the up antiquark carries charge ?
2
⁄
3
), color charge, and baryon number. There are six
flavors
of quarks; the three positively charged quarks are called "up-type quarks" while the three negatively charged quarks are called "down-type quarks".
Quarks
Generation
|
Name
|
Symbol
|
Antiparticle
|
Spin
|
Charge
(
e
)
|
Mass (
MeV
/
c
2
)
[5]
|
1
|
up
|
u
|
u
|
1
⁄
2
|
+
2
⁄
3
|
2.2
+0.6
?0.4
|
down
|
d
|
d
|
1
⁄
2
|
?
1
⁄
3
|
4.6
+0.5
?0.4
|
2
|
charm
|
c
|
c
|
1
⁄
2
|
+
2
⁄
3
|
1280
±
30
|
strange
|
s
|
s
|
1
⁄
2
|
?
1
⁄
3
|
96
+8
?4
|
3
|
top
|
t
|
t
|
1
⁄
2
|
+
2
⁄
3
|
173
100
±
600
|
bottom
|
b
|
b
|
1
⁄
2
|
?
1
⁄
3
|
4180
+40
?30
|
Leptons
[
edit
]
Leptons
do not interact via the
strong interaction
. Their respective
antiparticles
are the
antileptons
, which are identical, except that they carry the opposite electric charge and lepton number. The antiparticle of an
electron
is an antielectron, which is almost always called a "
positron
" for historical reasons. There are six leptons in total; the three charged leptons are called "electron-like leptons", while the neutral leptons are called "
neutrinos
". Neutrinos are known to
oscillate
, so that neutrinos of definite
flavor
do not have definite mass: Instead, they exist in a superposition of mass
eigenstates
. The hypothetical heavy right-handed neutrino, called a "
sterile neutrino
", has been omitted.
- ^
A precise value of the electron mass is
0.510
998
950
69
(16)
MeV/
c
2
.
[6]
- ^
A precise value of the muon mass is
105.658
3755
(23)
MeV/
c
2
.
[7]
Bosons
[
edit
]
Bosons
are one of the two fundamental particles having integral spinclasses of particles, the other being
fermions
. Bosons are characterized by
Bose?Einstein statistics
and all have integer spins. Bosons may be either elementary, like
photons
and
gluons
, or composite, like
mesons
.
According to the
Standard Model
, the elementary bosons are:
The
Higgs boson
is postulated by the
electroweak theory
primarily to explain the origin of
particle masses
. In a process known as the "
Higgs mechanism
", the Higgs boson and the other gauge bosons in the Standard Model acquire mass via
spontaneous symmetry breaking
of the SU(2) gauge symmetry. The
Minimal Supersymmetric Standard Model
(MSSM) predicts several Higgs bosons. On 4 July 2012, the discovery of a new particle with a mass between
125 and 127 GeV/
c
2
was announced; physicists suspected that it was the Higgs boson. Since then, the particle has been shown to behave, interact, and decay in many of the ways predicted for Higgs particles by the Standard Model, as well as having even parity and zero spin, two fundamental attributes of a Higgs boson. This also means it is the first elementary scalar particle discovered in nature.
Elementary bosons responsible for the four
fundamental forces
of nature are called
force particles
(
gauge bosons
).
Strong interaction
is mediated by the
gluon
,
weak interaction
is mediated by the W and Z bosons.
Hypothetical particles
[
edit
]
Graviton
[
edit
]
Name
|
Symbol
|
Antiparticle
|
Spin
|
Charge (
e
)
|
Mass (GeV/
c
2
)
[5]
|
Interaction mediated
|
Observed
|
graviton
|
G
|
self
|
2
|
0
|
0
|
gravitation
|
No
|
The
graviton
is a hypothetical particle that has been included in some extensions to the standard model to mediate the
gravitational
force. It is in a peculiar category between known and hypothetical particles: As an unobserved particle that is not predicted by, nor required for the
Standard Model
, it belongs in the table of hypothetical particles, below. But gravitational force itself is a certainty, and expressing that known force in the framework of a
quantum field theory
requires a boson to mediate it.
If it exists, the graviton is expected to be
massless
because the gravitational force has a very long range, and appears to propagate at the speed of light. The graviton must be a
spin
-2
boson
because the source of gravitation is the
stress?energy tensor
, a second-order
tensor
(compared with
electromagnetism
's spin-1
photon
, the source of which is the
four-current
, a first-order tensor). Additionally, it can be shown that any massless spin-2 field would give rise to a force indistinguishable from gravitation, because a massless spin-2 field would couple to the stress?energy tensor in the same way that gravitational interactions do. This result suggests that, if a massless spin-2 particle is discovered, it must be the graviton.
[8]
Particles predicted by supersymmetric theories
[
edit
]
Supersymmetric
theories predict the existence of more particles, none of which have been confirmed experimentally.
Superpartners (Sparticles)
Superpartner
|
Spin
|
Notes
|
superpartner of:
|
chargino
|
?1?
/
2
|
The charginos are
superpositions
of the
superpartners
of charged Standard Model bosons: charged
Higgs boson
and
W boson
.
The
MSSM
predicts two pairs of charginos.
|
charged bosons
|
gluino
|
?1?
/
2
|
Eight
gluons
and eight gluinos.
|
gluon
|
gravitino
|
?3?
/
2
|
Predicted by
supergravity
(
SUGRA
). The
graviton
is hypothetical, too ? see previous table.
|
graviton
|
Higgsino
|
?1
/
?2
|
For supersymmetry there is a need for several Higgs bosons, neutral and charged, according with their superpartners.
|
Higgs boson
|
neutralino
|
?1?
/
2
|
The neutralinos are
superpositions
of the
superpartners
of neutral Standard Model bosons: neutral
Higgs boson
,
Z boson
and
photon
.
The lightest neutralino is a leading candidate for
dark matter
.
The
MSSM
predicts four neutralinos.
|
neutral bosons
|
photino
|
?1?
/
2
|
Mixing with zino and neutral Higgsinos for neutralinos.
|
photon
|
sleptons
|
0
|
The superpartners of the
leptons
(electron, muon, tau) and the neutrinos.
|
leptons
|
sneutrino
|
0
|
Introduced by many extensions of the Standard Supermodel, and may be needed to explain the
LSND
results.
A special role has the sterile sneutrino, the supersymmetric counterpart of the hypothetical right-handed neutrino, called the "
sterile neutrino
".
|
neutrino
|
squarks
|
0
|
The stop squark (superpartner of the
top quark
) is thought to have a low mass and is often the subject of experimental searches.
|
quarks
|
wino, zino
|
?1?
/
2
|
The charged wino mixing with the charged Higgsino for charginos, for the zino see line above.
|
W
±
and Z
0
bosons
|
Just as the photon, Z boson and W
±
bosons are superpositions of the B
0
, W
0
, W
1
, and W
2
fields, the photino, zino, and wino
±
are superpositions of the bino
0
, wino
0
, wino
1
, and wino
2
. No matter if one uses the original gauginos or this superpositions as a basis, the only predicted physical particles are neutralinos and charginos as a superposition of them together with the Higgsinos.
Other hypothetical bosons and fermions
[
edit
]
Other theories predict the existence of additional elementary bosons and fermions, with some theories also postulating additional superpartners for these particles:
Other hypothetical elementary particles
[
edit
]
Composite particles
[
edit
]
Composite particles are
bound states
of elementary particles.
Hadrons
[
edit
]
Hadrons
are defined as
strongly interacting
composite particles
. Hadrons are either:
Quark models
, first proposed in 1964 independently by
Murray Gell-Mann
and
George Zweig
(who called quarks "aces"), describe the known hadrons as composed of valence
quarks
and/or antiquarks, tightly bound by the
color force
, which is mediated by
gluons
. (The interaction between quarks and gluons is described by the theory of
quantum chromodynamics
.) A "sea" of virtual quark-antiquark pairs is also present in each hadron.
Baryons
[
edit
]
Ordinary
baryons
(composite
fermions
) contain three valence quarks or three valence antiquarks each.
- Nucleons
are the fermionic constituents of normal atomic nuclei:
- Protons
, composed of two up and one down quark (uud)
- Neutrons
, composed of two down and one up quark (ddu)
- Hyperons
, such as the Λ, Σ, Ξ, and Ω particles, which contain one or more
strange quarks
, are short-lived and heavier than nucleons. Although not normally present in atomic nuclei, they can appear in short-lived
hypernuclei
.
- A number of
charmed
and
bottom
baryons have also been observed.
- Pentaquarks
consist of four valence quarks and one valence antiquark.
- Other
exotic baryons
may also exist.
Mesons
[
edit
]
Ordinary
mesons
are made up of a
valence quark
and a valence
antiquark
. Because mesons have integer
spin
(0 or 1) and are not themselves elementary particles, they are classified as “composite“
bosons
, although being made of
elementary
fermions
. Examples of mesons include the
pion
,
kaon
, and the
J/ψ
. In
quantum hadrodynamics
, mesons mediate the
residual strong force
between nucleons.
At one time or another, positive
signatures
have been reported for all of the following
exotic mesons
but their existences have yet to be confirmed.
- A
tetraquark
consists of two valence quarks and two valence antiquarks;
- A
glueball
is a bound state of gluons with no valence quarks;
- Hybrid
mesons consist of one or more valence quark?antiquark pairs and one or more real gluons.
Atomic nuclei
[
edit
]
Atomic nuclei
typically consist of protons and neutrons, although exotic nuclei may consist of other baryons, such as
hypertriton
which contains a
hyperon
. These baryons (protons, neutrons, hyperons, etc.) which comprise the nucleus are called nucleons. Each type of nucleus is called a "
nuclide
", and each nuclide is defined by the specific number of each type of nucleon.
- "
Isotopes
" are nuclides which have the same number of protons but differing numbers of neutrons.
- Conversely, "
isotones
" are nuclides which have the same number of neutrons but differing numbers of protons.
- "
Isobars
" are nuclides which have the same total number of nucleons but which differ in the number of each type of nucleon.
Nuclear reactions
can change one nuclide into another.
Atoms
[
edit
]
Atoms
are the smallest neutral particles into which matter can be divided by
chemical reactions
. An atom consists of a small, heavy nucleus surrounded by a relatively large, light cloud of electrons. An atomic nucleus consists of 1 or more protons and 0 or more neutrons. Protons and neutrons are, in turn, made of quarks. Each type of atom corresponds to a specific
chemical element
. To date, 118 elements have been discovered or created.
Exotic atoms
may be composed of particles in addition to or in place of protons, neutrons, and electrons, such as hyperons or muons. Examples include
pionium
(
π
−
π
+
) and
quarkonium
atoms.
Leptonic atoms
[
edit
]
Leptonic atoms, named using -
onium
, are exotic atoms constituted by the bound state of a lepton and an antilepton. Examples of such atoms include
positronium
(
e
−
e
+
),
muonium
(
e
−
μ
+
), and "
true muonium
" (
μ
−
μ
+
). Of these positronium and muonium have been experimentally observed, while "true muonium" remains only theoretical.
Molecules
[
edit
]
Molecules
are the smallest particles into which a substance can be divided while maintaining the chemical properties of the substance. Each type of molecule corresponds to a specific
chemical substance
. A molecule is a composite of two or more atoms. Atoms are combined in a fixed proportion to form a molecule. Molecule is one of the most basic units of matter.
Ions
[
edit
]
Ions
are charged atoms (
monatomic ions
) or molecules (
polyatomic ions
). They include cations which have a net positive charge, and anions which have a net negative charge.
Quasiparticles
[
edit
]
Quasiparticles
are effective particles that exist in many particle systems. The field equations of
condensed matter physics
are remarkably similar to those of high energy particle physics. As a result, much of the theory of particle physics applies to condensed matter physics as well; in particular, there are a selection of field excitations, called
quasi-particles
, that can be created and explored. These include:
- Anyons
are a generalization of fermions and bosons in two-dimensional systems like sheets of
graphene
that obeys
braid statistics
.
- Dislons
are localized collective excitations of a crystal dislocation around the static displacement.
- Excitons
are bound states of an
electron
and a
hole
.
- Hopfions
are topological solitons which are the 3D counterpart of the skyrmion.
- Magnons
are coherent excitations of electron spins in a material.
- Phonons
are vibrational modes in a
crystal lattice
.
- Plasmons
are coherent excitations of a
plasma
.
- Plektons
are theoretical kind of particle discussed as a generalization of the braid statistics of the anyon to more than two dimensions.
- Polaritons
are mixtures of
photons
with other quasi-particles.
- Polarons
are moving, charged (quasi-) particles that are surrounded by ions in a material.
- Skyrmions
are a topological solution of the
pion
field, used to model the low-energy properties of the
nucleon
, such as the axial vector current coupling and the mass.
Dark matter candidates
[
edit
]
The following categories are not unique or distinct: For example, either a
WIMP
or a
WISP
is also a
FIP
.
- A
WIMP
(weakly interacting massive particle) is any one of a number of particles that might explain dark matter (such as the
neutralino
or the
sterile neutrino
)
- A
WISP
(weakly interacting slender particle) is any one of a number of low mass particles that might explain dark matter (such as the
axion
)
- A GIMP (gravitationally interacting massive particle) is a particle which provides an alternative explanation of dark matter, instead of the aforementioned WIMP
- A
SIMP
(strongly interacting massive particle) is a particle that
interact strongly
between themselves and weakly with ordinary matter and could form dark matter
- A
SMP
(stable massive particle) is a particle that is long-lived and has appreciable mass that could be dark matter
- A
FIP
(feebly interacting particle) is a particle that interacts very weakly with conventional matter and could account for dark matter
- A
LSP
(lightest
supersymmetric particle
) is a particle found in
supersymmetric models
as a contender of WIMPs
Dark energy candidates
[
edit
]
Classification by speed
[
edit
]
Other
[
edit
]
- Calorons
, finite temperature generalization of instantons.
- Dyons
are hypothetical particles with both electric and magnetic charges.
- Geons
are electromagnetic or gravitational waves which are held together in a confined region by the gravitational attraction of their own field of energy.
- Goldstone bosons
are a massless excitation of a field that has been
spontaneously broken
. The
pions
are quasi-goldstone bosons (quasi- because they are not exactly massless) of the broken
chiral
isospin
symmetry of
quantum chromodynamics
.
- Goldstinos
are
fermions
produced by the spontaneous breaking of
supersymmetry
; they are the supersymmetric counterpart of Goldstone bosons.
- Sphalerons
are a field configuration which is a saddle point of the
Yang?Mills field equations
. Sphalerons are used in nonperturbative calculations of non-tunneling rates.
- Instantons
, a field configuration which is a local minimum of the Yang?Mills field equation. Instantons are used in nonperturbative calculations of tunneling rates.
- Meron
, a field configuration which is a non-self-dual solution of the Yang?Mills field equation. The instanton is believed to be composed of two merons.
- Parton
, is a generic term coined by
Feynman
for the sub-particles making up a composite particle ? at that time a baryon ? hence, it originally referred to what are now called "
quarks
" and "
gluons
".
- Pomerons
, used to explain the
elastic scattering
of hadrons and the location of
Regge poles
in
Regge theory
. A counterpart to odderons.
- Odderon
, a particle composed of an odd number of gluons, detected in 2021. A counterpart to pomerons.
- Minicharged particle
are hypothetical subatomic particles charged with a tiny fraction of the electron charge.
- Continuous spin particle
are hypothetical massless particles related to the classification of the representations of the
Poincare group
See also
[
edit
]
References
[
edit
]
- ^
Sylvie Braibant; Giorgio Giacomelli; Maurizio Spurio (2012).
Particles and Fundamental Interactions: An Introduction to Particle Physics
(1st ed.).
Springer
. p. 1.
ISBN
978-94-007-2463-1
.
- ^
Khachatryan, V.; et al. (CMS Collaboration) (2012). "Observation of a new boson at a mass of 125 GeV with the CMS experiment at the LHC".
Physics Letters B
.
716
(2012): 30?61.
arXiv
:
1207.7235
.
Bibcode
:
2012PhLB..716...30C
.
doi
:
10.1016/j.physletb.2012.08.021
.
- ^
Abajyan, T.; et al. (ATLAS Collaboration) (2012). "Observation of a new particle in the search for the Standard Model Higgs boson with the ATLAS detector at the LHC".
Physics Letters B
.
716
(2012): 1?29.
arXiv
:
1207.7214
.
Bibcode
:
2012PhLB..716....1A
.
doi
:
10.1016/j.physletb.2012.08.020
.
S2CID
119169617
.
- ^
Kayser, Boris (2010). "Two Questions About Neutrinos".
arXiv
:
1012.4469
[
hep-ph
].
- ^
a
b
c
d
Particle Data Group (2016).
"Review of Particle Physics"
.
Chinese Physics C
.
40
(10): 100001.
Bibcode
:
2016ChPhC..40j0001P
.
doi
:
10.1088/1674-1137/40/10/100001
.
hdl
:
1983/c6dc3926-daee-4d0e-9149-5ff3a8120574
.
S2CID
125766528
.
- ^
"2022 CODATA Value: electron mass energy equivalent in MeV"
.
The NIST Reference on Constants, Units, and Uncertainty
.
NIST
. May 2024
. Retrieved
2024-05-18
.
- ^
"2022 CODATA Value: muon mass energy equivalent in MeV"
.
The NIST Reference on Constants, Units, and Uncertainty
.
NIST
. May 2024
. Retrieved
2024-05-18
.
- ^
For a comparison of the geometric derivation and the (non-geometric) spin-2 field derivation of general relativity, refer to box 18.1 (and also 17.2.5) of
Misner, C. W.
;
Thorne, K. S.
;
Wheeler, J. A.
(1973).
Gravitation
.
W. H. Freeman
.
ISBN
0-7167-0344-0
.
- ^
Maartens, R. (2004).
"Brane-world gravity"
(PDF)
.
Living Reviews in Relativity
.
7
(1): 7.
arXiv
:
gr-qc/0312059
.
Bibcode
:
2004LRR.....7....7M
.
doi
:
10.12942/lrr-2004-7
.
PMC
5255527
.
PMID
28163642
.
- ^
Salam, A. (1966). "Magnetic monopole and two photon theories of C-violation".
Physics Letters
.
22
(5): 683?684.
Bibcode
:
1966PhL....22..683S
.
doi
:
10.1016/0031-9163(66)90704-9
.