Editing Particle physics (section)

== Subatomic particles ==
{{Cleanup rewrite|2=section|date=August 2024}}
{| class="wikitable" style="float:right; margin-left:1em; background:#FFF;"
|+ Elementary Particles
|-
!
! scope="col" | [[Generation (particle physics)|Types]]
! scope="col" | [[Generation (particle physics)|Generations]]
! scope="col" | [[Antiparticle]]
! scope="col" | [[Color charge|Colours]]
! scope="col" | Total
|-
! scope="row" style="background:#DAF;" | [[Quark]]s
| rowspan="2" align="center"| 2
| rowspan="2" align="center"| 3
| align="center"|Pair
| align="center"|3
| align="center"|36
|-
! scope="row" style="background:#AF7;" | [[Lepton]]s
| align="center"|Pair
| align="center"|None
| align="center"|12
|-
! scope="row" style="background:#F97;" | [[Gluon]]s
|rowspan="5" align="center"|1
|rowspan="5" align="center"|None
| align="center"|Own
| align="center"|[[Gluon#Eight color states|8]]
| align="center"|8
|-
! scope="row" style="background:#F97;" | [[Photon]]
| align="center"|Own
| align="center" rowspan="4"|None
| align="center"|1
|-
! scope="row" style="background:#F97;" | [[W and Z bosons|Z Boson]]
| align="center"|Own
| align="center"|1
|-
! scope="row" style="background:#F97;" | [[W and Z bosons|W Boson]]
| align="center"|Pair
| align="center"|2
|-
! scope="row" style="background:#FE7;" | [[Higgs boson|Higgs]]
| align="center"|Own
| align="center"|1
|-
! colspan="5" align="right" ! scope="col" | Total number of (known) elementary particles:
| align="center"|'''61'''
|}
Modern particle physics research is focused on [[subatomic particle]]s, including atomic constituents, such as [[electron]]s, [[proton]]s, and [[neutron]]s (protons and neutrons are composite particles called [[baryon]]s, made of [[quark]]s), that are produced by [[Radioactive decay|radioactive]] and [[scattering]] processes; such particles are [[photon]]s, [[neutrino]]s, and [[muon]]s, as well as a wide range of [[exotic particle]]s.<ref>{{cite book |last1=Terranova |first1=Francesco |title=A Modern Primer in Particle and Nuclear Physics. |date=2021 |publisher=Oxford Univ. Press |isbn=978-0-19-284524-5}}</ref> All particles and their interactions observed to date can be described almost entirely by the Standard Model.<ref name="Baker p 120" />

Dynamics of particles are also governed by [[quantum mechanics]]; they exhibit [[wave–particle duality]], displaying particle-like behaviour under certain experimental conditions and [[wave]]-like behaviour in others. In more technical terms, they are described by [[quantum state]] vectors in a [[Hilbert space]], which is also treated in [[quantum field theory]]. Following the convention of particle physicists, the term ''[[elementary particle]]s'' is applied to those particles that are, according to current understanding, presumed to be indivisible and not composed of other particles.<ref name="braibant"/>

=== Quarks and leptons ===
{{Main|Quark|Lepton}}
[[File:Beta_Negative_Decay.svg|thumb|A [[Feynman diagram]] of the [[Beta decay|{{SubatomicParticle|Beta-}}&nbsp;decay]], showing a neutron (n, udd) converted into a proton (p, udu). "u" and "d" are the [[Up quark|up]] and [[down quark]]s, "{{Subatomic particle|electron}}" is the [[electron]], and "{{Subatomic particle|Electron antineutrino}}" is the [[Electron Antineutrino|electron antineutrino]].]]
Ordinary [[matter]] is made from first-[[Generation (particle physics)|generation]] quarks ([[Up quark|up]], [[Down quark|down]]) and leptons ([[electron]], [[electron neutrino]]).<ref name="Povh02">{{cite book |author=Povh |first1=B. |title=Particles and Nuclei: An Introduction to the Physical Concepts |last2=Rith |first2=K. |last3=Scholz |first3=C. |last4=Zetsche |first4=F. |last5=Lavelle |first5=M. |date=2004 |publisher=Springer |isbn=978-3-540-20168-7 |edition=4th |chapter=Part I: Analysis: The building blocks of matter |quote=Ordinary matter is composed entirely of first-generation particles, namely the u and d quarks, plus the electron and its neutrino. |access-date=28 July 2022 |chapter-url=https://books.google.com/books?id=rJe4k8tkq7sC&q=povh+%22building+blocks+of+matter%22&pg=PA9 |archive-url=https://web.archive.org/web/20220422024501/https://books.google.com/books?id=rJe4k8tkq7sC&q=povh+%22building+blocks+of+matter%22&pg=PA9 |archive-date=22 April 2022 |url-status=live}}</ref> Collectively, quarks and leptons are called [[fermion]]s, because they have a [[quantum spin]] of [[half-integer]]s (−1/2, 1/2, 3/2, etc.). This causes the fermions to obey the [[Pauli exclusion principle]], where no two particles may occupy the same [[quantum state]].<ref>{{cite book |author=Peacock |first=K. A. |url=https://archive.org/details/quantumrevolutio00peac |title=The Quantum Revolution |publisher=[[Greenwood Publishing Group]] |year=2008 |isbn=978-0-313-33448-1 |page=[https://archive.org/details/quantumrevolutio00peac/page/n143 125] |url-access=limited}}</ref> Quarks have fractional [[Elementary charge|elementary electric charge]] (−1/3 or 2/3)<ref>{{cite book |author=Quigg |first=C. |title=The New Physics for the Twenty-First Century |publisher=[[Cambridge University Press]] |year=2006 |isbn=978-0-521-81600-7 |editor=G. Fraser |page=91 |chapter=Particles and the Standard Model}}</ref> and leptons have whole-numbered electric charge (0 or -1).<ref>{{Cite book |last1=Serway |first1=Raymond A. |url=https://books.google.com/books?id=ecYWAAAAQBAJ |title=Physics for Scientists and Engineers, Volume 2 |last2=Jewett |first2=John W. |date=2013-01-01 |publisher=Cengage Learning |isbn=978-1-285-62958-2 |language=en}}</ref> Quarks also have [[color charge]], which is labeled arbitrarily with no correlation to actual light [[color]] as red, green and blue.<ref name="R. Nave">{{cite web |author=Nave |first=R. |title=The Color Force |url=http://hyperphysics.phy-astr.gsu.edu/hbase/forces/color.html#c2 |url-status=live |archive-url=https://web.archive.org/web/20181007142048/http://hyperphysics.phy-astr.gsu.edu/hbase/Forces/color.html#c2 |archive-date=7 October 2018 |access-date=2009-04-26 |work=[[HyperPhysics]] |publisher=[[Georgia State University]], Department of Physics and Astronomy}}</ref> Because the interactions between the quarks store energy which can convert to other particles when the quarks are far apart enough, quarks cannot be observed independently. This is called [[color confinement]].<ref name="R. Nave"/>

There are three known generations of quarks (up and down, [[Strange quark|strange]] and [[Charm quark|charm]], [[Top quark|top]] and [[Bottom quark|bottom]]) and leptons (electron and its neutrino, [[muon]] and [[Muon neutrino|its neutrino]], [[Tau (particle)|tau]] and [[Tau neutrino|its neutrino]]), with strong indirect evidence that a fourth generation of fermions does not exist.<ref>{{cite journal |author=Decamp |first=D. |year=1989 |title=Determination of the number of light neutrino species |url=https://cds.cern.ch/record/201511 |journal=[[Physics Letters B]] |volume=231 |issue=4 |pages=519–529 |bibcode=1989PhLB..231..519D |doi=10.1016/0370-2693(89)90704-1 |hdl-access=free |hdl=11384/1735}}</ref>

=== Bosons ===
{{Main|Boson}}

Bosons are the [[Force carrier|mediators or carriers]] of fundamental interactions, such as [[electromagnetism]], the [[weak interaction]], and the [[strong interaction]].<ref name="DarkMatter">{{cite book |author=Carroll, Sean |authorlink = Sean M. Carroll | title=Guidebook |publisher=The Teaching Company |year=2007 |isbn=978-1598033502 |series=Dark Matter, Dark Energy: The dark side of the universe |at=Part&nbsp;2, p.&nbsp;43 |quote=...&nbsp;boson: A force-carrying particle, as opposed to a matter particle (fermion). Bosons can be piled on top of each other without limit. Examples are photons, gluons, gravitons, weak bosons, and the Higgs boson. The spin of a boson is always an integer: 0, 1, 2, and so on&nbsp;...}}</ref> Electromagnetism is mediated by the [[photon]], the [[Quantum|quanta]] of [[light]].<ref>"Role as gauge boson and polarization" §5.1 in {{cite book |last1=Aitchison |first1=I. J. R. |url={{google books |plainurl=y |id=ZJ-ZY8NW9TIC}} |title=Gauge Theories in Particle Physics |last2=Hey |first2=A. J. G. |publisher=[[IOP Publishing]] |year=1993 |isbn=978-0-85274-328-7}}</ref>{{rp|29–30}} The weak interaction is mediated by the [[W and Z bosons]].<ref>{{cite book |first=Peter |last=Watkins |url=https://books.google.com/books?id=J808AAAAIAAJ&pg=PA70 |title=Story of the W and Z |publisher=[[Cambridge University Press]] |year=1986 |isbn=9780521318754 |location=Cambridge |page=70 |access-date=28 July 2022 |archive-url=https://web.archive.org/web/20121114055111/http://books.google.co.uk/books?id=J808AAAAIAAJ&pg=PA70 |archive-date=14 November 2012 |url-status=live}}</ref> The strong interaction is mediated by the [[gluon]], which can link quarks together to form composite particles.<ref name="HyperPhysics">{{cite web |author=Nave |first=C. R. |title=The Color Force |url=http://hyperphysics.phy-astr.gsu.edu/hbase/forces/color.html |url-status=live |archive-url=https://web.archive.org/web/20181007142048/http://hyperphysics.phy-astr.gsu.edu/hbase/Forces/color.html |archive-date=7 October 2018 |access-date=2012-04-02 |work=[[HyperPhysics]] |publisher=[[Georgia State University]], Department of Physics}}</ref> Due to the aforementioned color confinement, gluons are never observed independently.<ref name=":0">{{cite journal |last=Debrescu |first=B. A. |year=2005 |title=Massless Gauge Bosons Other Than The Photon |journal=[[Physical Review Letters]] |volume=94 |issue=15 |page=151802 |arxiv=hep-ph/0411004 |bibcode=2005PhRvL..94o1802D |doi=10.1103/PhysRevLett.94.151802 |pmid=15904133 |s2cid=7123874}}</ref> The [[Higgs boson]] gives mass to the W and Z bosons via the [[Higgs mechanism]]<ref name="PDG">{{cite web |author1=Bernardi, G. |author2=Carena, M. |author3=Junk, T. |year=2007 |title=Higgs bosons: Theory and searches |url=http://pdg.lbl.gov/2008/reviews/higgs_s055.pdf |url-status=live |archive-url=https://web.archive.org/web/20181003190309/http://pdg.lbl.gov/2008/reviews/higgs_s055.pdf |archive-date=3 October 2018 |access-date=28 July 2022 |series=Review: Hypothetical particles and Concepts |publisher=Particle Data Group}}</ref> – the gluon and photon are expected to be [[Massless particle|massless]].<ref name=":0" /> All bosons have an integer quantum spin (0 and 1) and can have the same [[quantum state]].<ref name="DarkMatter" />

=== Antiparticles and color charge ===
{{Main|Antiparticle|Color charge}}

Most aforementioned particles have corresponding [[antiparticle]]s, which compose [[antimatter]]. Normal particles have positive [[Lepton number|lepton]] or [[baryon number]], and antiparticles have these numbers negative.<ref>{{cite journal |last=Tsan |first=Ung Chan |date=2013 |title=Mass, Matter, Materialization, Mattergenesis and Conservation of Charge |journal=International Journal of Modern Physics E |volume=22 |issue=5 |page=1350027 |bibcode=2013IJMPE..2250027T |doi=10.1142/S0218301313500274 |quote=Matter conservation means conservation of baryonic number ''A'' and leptonic number ''L'', ''A'' and ''L'' being algebraic numbers. Positive ''A'' and ''L'' are associated to matter particles, negative ''A'' and ''L'' are associated to antimatter particles. All known interactions do conserve matter.}}</ref> Most properties of corresponding antiparticles and particles are the same, with a few gets reversed; the electron's antiparticle, positron, has an opposite charge. To differentiate between antiparticles and particles, a plus or negative sign is added in [[superscript]]. For example, the electron and the positron are denoted {{Subatomic particle|Electron}} and {{Subatomic particle|positron}}.<ref name="raith">{{cite book |last1=Raith |first1=W. |title=Constituents of Matter: Atoms, Molecules, Nuclei and Particles |last2=Mulvey |first2=T. |publisher=[[CRC Press]] |year=2001 |isbn=978-0-8493-1202-1 |pages=777–781}}</ref> However, in the case that the particle has a charge of 0 (equal to that of the antiparticle), the antiparticle is denoted with a line above the symbol. As such, an electron neutrino is {{Math|{{Subatomic Particle|Electron Neutrino}}}}, whereas its antineutrino is {{Math|{{Subatomic Particle|Electron Antineutrino}}}}. When a particle and an antiparticle interact with each other, they are [[Annihilation|annihilated]] and convert to other particles.<ref>{{cite web |title=Antimatter |url=http://www.lbl.gov/abc/Antimatter.html |url-status=live |archive-url=https://web.archive.org/web/20080823180515/http://www.lbl.gov/abc/Antimatter.html |archive-date=23 August 2008 |access-date=3 September 2008 |publisher=[[Lawrence Berkeley National Laboratory]]}}</ref> Some particles, such as the photon or gluon, have no antiparticles.{{Citation needed|date=July 2022}}

Quarks and gluons additionally have color charges, which influences the strong interaction. Quark's color charges are called red, green and blue (though the particle itself have no physical color), and in antiquarks are called antired, antigreen and antiblue.<ref name="R. Nave"/> The gluon can have [[Gluon|eight color charges]], which are the result of quarks' interactions to form composite particles (gauge symmetry [[SU(3)]]).<ref name="PeskinSchroeder">Part III of {{cite book |last1=Peskin |first1=M. E. |url=https://archive.org/details/introductiontoqu0000pesk |title=An Introduction to Quantum Field Theory |last2=Schroeder |first2=D. V. |publisher=[[Addison–Wesley]] |year=1995 |isbn=978-0-201-50397-5 |url-access=registration}}</ref>

=== Composite ===
{{Main|Composite particle}}
[[File:Quark_structure_proton.svg|thumb|A [[proton]] consists of two up quarks and one down quark, linked together by [[gluon]]s. The quarks' color charge are also visible.]]
The [[neutron]]s and [[proton]]s in the [[Atomic nucleus|atomic nuclei]] are [[baryon]]s – the neutron is composed of two down quarks and one up quark, and the proton is composed of two up quarks and one down quark.<ref name="Knowing2">{{cite book |author=Munowitz |first=M. |title=Knowing |publisher=[[Oxford University Press]] |year=2005 |isbn=0195167376 |page=35}}</ref> A baryon is composed of three quarks, and a [[meson]] is composed of two quarks (one normal, one anti). Baryons and mesons are collectively called [[hadron]]s. Quarks inside hadrons are governed by the strong interaction, thus are subjected to [[quantum chromodynamics]] (color charges). The [[Bound state|bounded]] quarks must have their color charge to be neutral, or "white" for analogy with [[Additive color|mixing the primary colors]].<ref>{{cite book |author=Schumm |first=B. A. |url=https://archive.org/details/deepdownthingsbr00schu/page/131 |title=Deep Down Things |publisher=[[Johns Hopkins University Press]] |year=2004 |isbn=978-0-8018-7971-5 |pages=[https://archive.org/details/deepdownthingsbr00schu/page/131 131–132]}}</ref> More [[exotic hadron]]s can have other types, arrangement or number of quarks ([[tetraquark]], [[pentaquark]]).<ref>{{cite journal |last=Close |first=F. E. |year=1988 |title=Gluonic Hadrons |journal=Reports on Progress in Physics |volume=51 |pages=833–882 |bibcode=1988RPPh...51..833C |doi=10.1088/0034-4885/51/6/002 |number=6|s2cid=250819208 }}</ref>

An atom is made from protons, neutrons and electrons.<ref>{{Cite book |last1=Kofoed |first1=Melissa |last2=Miller |first2=Shawn |date=July 2024 |title=Introductory Chemistry |url=https://uen.pressbooks.pub/introductorychemistry/}}</ref> By modifying the particles inside a normal atom, [[exotic atom]]s can be formed.<ref>§1.8, ''Constituents of Matter: Atoms, Molecules, Nuclei and Particles'', Ludwig Bergmann, Clemens Schaefer, and Wilhelm Raith, Berlin, Germany: Walter de Gruyter, 1997, {{ISBN|3-11-013990-1}}.</ref> A simple example would be the [[hydrogen-4.1]], which has one of its electrons replaced with a muon.<ref>{{Cite journal |last1=Fleming |first1=D. G. |last2=Arseneau |first2=D. J. |last3=Sukhorukov |first3=O. |last4=Brewer |first4=J. H. |last5=Mielke |first5=S. L. |last6=Schatz |first6=G. C. |last7=Garrett |first7=B. C. |last8=Peterson |first8=K. A. |last9=Truhlar |first9=D. G. |date=28 Jan 2011 |title=Kinetic Isotope Effects for the Reactions of Muonic Helium and Muonium with H<sub>2</sub> |url=https://www.science.org/doi/abs/10.1126/science.1199421 |journal=Science |volume=331 |issue=6016 |pages=448–450 |doi=10.1126/science.1199421 |pmid=21273484 |bibcode=2011Sci...331..448F |s2cid=206530683|url-access=subscription }}</ref>

=== Hypothetical ===
The [[graviton]] is a hypothetical particle that can mediate the gravitational interaction, but it has not been detected or completely reconciled with current theories.<ref>{{cite news |last=Sokal |first=A. |author-link=Alan Sokal |date=July 22, 1996 |title=Don't Pull the String Yet on Superstring Theory |work=[[The New York Times]] |url=https://query.nytimes.com/gst/fullpage.html?res=9D0DE7DB1639F931A15754C0A960958260 |url-status=live |access-date=March 26, 2010 |archive-url=https://web.archive.org/web/20081207212917/https://query.nytimes.com/gst/fullpage.html?res=9D0DE7DB1639F931A15754C0A960958260 |archive-date=7 December 2008}}</ref> Many other hypothetical particles have been proposed to address the limitations of the Standard Model. Notably, [[Supersymmetry|supersymmetric]] particles aim to solve the [[hierarchy problem]], [[axion]]s address the [[strong CP problem]], and various other particles are proposed to explain the origins of [[dark matter]] and [[dark energy]].