Editing Standard Model (section)

== Historical background ==
{{See also|History of quantum field theory|History of subatomic physics|Julian Schwinger|John Clive Ward}}
In 1928, [[Paul Dirac]] introduced the [[Dirac equation]], which implied the existence of [[antimatter]].

In 1954, [[Yang Chen-Ning]] and [[Robert Mills (physicist)|Robert Mills]] extended the concept of [[gauge theory]] for [[abelian group]]s, e.g. [[quantum electrodynamics]], to [[nonabelian group]]s to provide an explanation for [[strong interaction]]s.<ref name="YM">{{cite journal |author-link1=Chen-Ning Yang |first1=C. N. |last1=Yang |author-link2=Robert Mills (physicist) |first2=R. |last2=Mills |title=Conservation of Isotopic Spin and Isotopic Gauge Invariance |journal=[[Physical Review]] |volume=96 |issue=1 |pages=191–195 |year=1954 |doi=10.1103/PhysRev.96.191|bibcode = 1954PhRv...96..191Y |doi-access=free }}</ref> In 1957, [[Chien-Shiung Wu]] demonstrated [[parity (physics)|parity]] was not conserved in the [[weak interaction]].<ref>{{cite web|last=Cho|first=Adrian|title=Postage stamp to honor female physicist who many say should have won the Nobel Prize|date=5 February 2021|url=https://www.science.org/content/article/postage-stamp-honor-female-physicist-who-many-say-should-have-won-nobel-prize}}</ref> 

In 1961, [[Sheldon Glashow]] combined the [[electromagnetism|electromagnetic]] and [[weak interaction]]s.<ref>
{{cite journal
 |author=S.L. Glashow
 |year=1961
 |title=Partial-symmetries of weak interactions
 |journal=[[Nuclear Physics (journal)|Nuclear Physics]]
 |volume=22 |issue=4 |pages=579–588
 |bibcode=1961NucPh..22..579G
 |doi=10.1016/0029-5582(61)90469-2
}}</ref> In 1964, [[Murray Gell-Mann]] and [[George Zweig]] introduced quarks and that same year [[Oscar W. Greenberg]] implicitly introduced color charge of quarks.<ref>{{Citation |last=Greenberg |first=Oscar Wallace |title=Color Charge Degree of Freedom in Particle Physics |date=2009 |work=Compendium of Quantum Physics |pages=109–111 |editor-last=Greenberger |editor-first=Daniel |url=https://link.springer.com/chapter/10.1007/978-3-540-70626-7_32 |access-date=2024-09-17 |place=Berlin, Heidelberg |publisher=Springer |language=en |doi=10.1007/978-3-540-70626-7_32 |isbn=978-3-540-70626-7 |editor2-last=Hentschel |editor2-first=Klaus |editor3-last=Weinert |editor3-first=Friedel|url-access=subscription }}</ref> In 1967 [[Steven Weinberg]]<ref>
{{cite journal
 |author=S. Weinberg
 |year=1967
 |title=A Model of Leptons
 |journal=[[Physical Review Letters]]
 |volume=19 |issue=21 |pages=1264–1266
 |bibcode=1967PhRvL..19.1264W
 |doi=10.1103/PhysRevLett.19.1264
|doi-access=free
 }}</ref> and [[Abdus Salam]]<ref>
{{cite conference
 |author=A. Salam
 |editor=N. Svartholm
 |year=1968
 |book-title=Elementary Particle Physics: Relativistic Groups and Analyticity
 |pages=367
 |conference=Eighth Nobel Symposium
 |publisher=Almquvist and Wiksell
 |location=Stockholm
}}</ref> incorporated the [[Higgs mechanism]]<ref name="Englert1964">
{{cite journal
 |author1=F. Englert |author2=R. Brout |year=1964
 |title=Broken Symmetry and the Mass of Gauge Vector Mesons
 |journal=[[Physical Review Letters]]
 |volume=13 |issue=9 |pages=321–323
 |bibcode=1964PhRvL..13..321E
 |doi=10.1103/PhysRevLett.13.321
|doi-access=free}}</ref><ref name="Peter W. Higgs 1964 508–509">
{{cite journal |author=P.W. Higgs |year=1964 |title=Broken Symmetries and the Masses of Gauge Bosons |journal=[[Physical Review Letters]] |volume=13 |issue=16 |pages=508–509 |bibcode=1964PhRvL..13..508H |doi=10.1103/PhysRevLett.13.508 |doi-access=free}}</ref><ref name="G.S. Guralnik, C.R. Hagen, T.W.B. Kibble 1964 585–587">
{{cite journal
 |author1=G.S. Guralnik |author2=C.R. Hagen |author3=T.W.B. Kibble |year=1964
 |title=Global Conservation Laws and Massless Particles
 |journal=[[Physical Review Letters]]
 |volume=13 |issue=20 |pages=585–587
 |bibcode=1964PhRvL..13..585G
 |doi=10.1103/PhysRevLett.13.585
|doi-access=free}}</ref> into Glashow's [[electroweak interaction]], giving it its modern form.

In 1970, Sheldon Glashow, John Iliopoulos, and Luciano Maiani introduced the [[GIM mechanism]], predicting the [[charm quark]].<ref name=":2">{{Cite journal |last=Weinberg |first=S. |date=2004-05-01 |title=The making of the Standard Model |url=https://link.springer.com/article/10.1140/epjc/s2004-01761-1 |journal=European Physical Journal C |language=en |volume=34 |issue=1 |pages=5–13 |doi=10.1140/epjc/s2004-01761-1 |arxiv=hep-ph/0401010 |bibcode=2004EPJC...34....5W |issn=1434-6052}}</ref> In 1973 Gross and Wilczek and Politzer independently discovered that non-Abelian gauge theories, like the color theory of the strong force, have [[asymptotic freedom]].<ref name=":2" />  In 1976, Martin Perl discovered the [[tau lepton]] at the [[SLAC National Accelerator Laboratory|SLAC]].<ref>{{Cite web |title=The Nobel Prize in Physics 1995 |url=https://www.nobelprize.org/prizes/physics/1995/perl/facts/#:~:text=In%20a%20series%20of%20experiments,alongside%20two%20previously%20known%20families. |access-date=2024-09-17 |website=NobelPrize.org |language=en-US}}</ref><ref>{{Cite web |last=magazine |first=STANFORD |date=2015-01-01 |title=In Memoriam |url=https://stanfordmag.org/contents/in-memoriam |access-date=2024-09-17 |website=stanfordmag.org |language=en}}</ref> In 1977, a team led by Leon Lederman at Fermilab discovered the bottom quark.<ref>{{Cite web |title=Inquiring Minds {{!}} Discoveries at Fermilab - The Bottom Quark |url=https://www.fnal.gov/pub/inquiring/physics/discoveries/bottom_quark.html |access-date=2024-09-17 |website=www.fnal.gov}}</ref>

The Higgs mechanism is believed to give rise to the [[mass]]es of all the [[elementary particle]]s in the Standard Model. This includes the masses of the [[W and Z bosons]], and the masses of the [[fermion]]s, i.e. the [[quark]]s and [[lepton]]s.

After the [[Neutral current|neutral weak currents]] caused by [[Subatomic particle|Z boson]] exchange [[Gargamelle|were discovered]] at [[CERN]] in 1973,<ref>
{{cite journal
 |author=F.J. Hasert |display-authors=etal 
 |year=1973
 |title=Search for elastic muon-neutrino electron scattering
 |journal=[[Physics Letters B]]
 |volume=46 |issue=1 |page=121
 |bibcode=1973PhLB...46..121H
 |doi=10.1016/0370-2693(73)90494-2
}}</ref><ref>
{{cite journal
 |author=F.J. Hasert |display-authors=etal 
 |year=1973
 |title=Observation of neutrino-like interactions without muon or electron in the Gargamelle neutrino experiment
 |journal=[[Physics Letters B]]
 |volume=46 |issue=1 |page=138
 |bibcode=1973PhLB...46..138H
 |doi=10.1016/0370-2693(73)90499-1
}}</ref><ref>
{{cite journal
 |author=F.J. Hasert
 |year=1974
 |title=Observation of neutrino-like interactions without muon or electron in the Gargamelle neutrino experiment
 |journal=[[Nuclear Physics B]]
 |volume=73 |issue=1 |page=1
 |bibcode=1974NuPhB..73....1H
 |doi=10.1016/0550-3213(74)90038-8
|display-authors=etal}}</ref><ref>{{cite web
 |author=D. Haidt
 |date=4 October 2004
 |title=The discovery of the weak neutral currents
 |url=http://cerncourier.com/cws/article/cern/29168
 |work=[[CERN Courier]]
 |access-date=8 May 2008
 |archive-date=20 May 2011
 |archive-url=https://web.archive.org/web/20110520115858/http://cerncourier.com/cws/article/cern/29168
 |url-status=dead
 }}</ref> the electroweak theory became widely accepted and Glashow, Salam, and Weinberg shared the 1979 [[Nobel Prize in Physics]] for discovering it. The W<sup>±</sup> and Z<sup>0</sup> [[boson]]s were discovered experimentally in 1983; and the ratio of their masses was found to be as the Standard Model predicted.<ref>{{cite journal|last1=Gaillard|first1=Mary K.|author-link1=Mary K. Gaillard|last2=Grannis|first2= Paul D. |last3=Sciulli|first3=Frank J.|title=The Standard Model of Particle Physics|date=January 1999|journal=Reviews of Modern Physics|doi=10.1103/RevModPhys.71.S96|volume=71|issue=2 |pages=S96–S111|arxiv=hep-ph/9812285|bibcode=1999RvMPS..71...96G|s2cid=119012610}}</ref>

The theory of the [[strong interaction]] (i.e. [[quantum chromodynamics]], QCD), to which many contributed, acquired its modern form in 1973–74 when [[asymptotic freedom]] was proposed<ref>
{{cite journal
 |author1=D.J. Gross |author2=F. Wilczek |year=1973
 |title=Ultraviolet behavior of non-abelian gauge theories
 |journal=[[Physical Review Letters]]
 |volume=30 |issue= 26|pages= 1343–1346
 |bibcode=1973PhRvL..30.1343G
 |doi=10.1103/PhysRevLett.30.1343
|doi-access=free}}</ref><ref>
{{cite journal
 |author=H.D. Politzer
 |year=1973
 |title=Reliable perturbative results for strong interactions
 |journal=[[Physical Review Letters]]
 |volume=30 |issue=26 |pages=1346–1349
 |bibcode=1973PhRvL..30.1346P
 |doi=10.1103/PhysRevLett.30.1346
|url=https://authors.library.caltech.edu/6668/1/POLprl73.pdf |archive-url=https://web.archive.org/web/20180719010018/https://authors.library.caltech.edu/6668/1/POLprl73.pdf |archive-date=2018-07-19 |url-status=live
 |doi-access=free
 }}</ref> (a development that made QCD the main focus of theoretical research)<ref>[[Dean Rickles]] (2014). ''A Brief History of String Theory: From Dual Models to M-Theory''. Springer, p. 11 n. 22.</ref> and experiments confirmed that the [[hadron]]s were composed of fractionally charged quarks.<ref>
{{cite journal
 |last1=Aubert |first1=J.
 |year=1974
 |title=Experimental Observation of a Heavy Particle J
 |journal=[[Physical Review Letters]]
 |volume=33 |issue=23 |pages=1404–1406
 |bibcode = 1974PhRvL..33.1404A
 |doi=10.1103/PhysRevLett.33.1404
|display-authors=etal|doi-access=free
 }}</ref><ref>
{{cite journal
 |last1=Augustin |first1=J.
 |year=1974
 |title=Discovery of a Narrow Resonance in e<sup>+</sup>e<sup>−</sup> Annihilation
 |journal=[[Physical Review Letters]]
 |volume=33 |issue=23 |pages=1406–1408
 |bibcode = 1974PhRvL..33.1406A
 |doi=10.1103/PhysRevLett.33.1406
 |display-authors=etal|doi-access=free
 }}</ref>

The term "Standard Model" was introduced by [[Abraham Pais]] and [[Sam Treiman]] in 1975,<ref>
{{cite journal |last1=Pais |first1=A. |last2=Treiman |first2=S. B. |year=1975 |title=How Many Charm Quantum Numbers are There? |journal=[[Physical Review Letters]] |volume=35 |issue=23 |pages=1556–1559 |doi=10.1103/PhysRevLett.35.1556 |bibcode=1975PhRvL..35.1556P |doi-access=}}</ref> with reference to the electroweak theory with four quarks.<ref>{{Cite book |last=Cao |first=Tian Yu |url=http://dx.doi.org/10.1017/9781108566926 |title=Conceptual Developments of 20th Century Field Theories |date=1 October 2019 |publisher=Cambridge University Press |isbn=978-1-108-56692-6 |publication-date=1998 |page=320|doi=10.1017/9781108566926 |bibcode=2019code.book.....C |s2cid=243686857 }}</ref> [[Steven Weinberg]] has since claimed priority, explaining that he chose the term Standard [[Model]] out of a sense of modesty<ref>A [[model]] is a representation of reality, whereas a [[theory]] is an explanation of reality; this Wikipedia article and some of the literature refers to the Standard Model as a theory.</ref><ref>{{Cite web |last=Weinberg |first=Steven |title=This World and the Universe |url=https://www.youtube.com/watch?v=Gnk0rnBQrR0&t=1080s |access-date=29 March 2022 |website=[[YouTube]] |date=20 April 2010 |publisher=Talks at Google}}</ref><ref>{{Cite web |year=2015 |title=World Science Festival |url=https://www.youtube.com/watch?v=g-y3DPJRVhE&t=435s |access-date=29 March 2022 |website=[[YouTube]]}}</ref>{{Better source needed|reason=The current source is insufficiently reliable ([[WP:NOTRS]]).|date=March 2022}} and used it in 1973 during a talk in Aix-en-Provence in France.<ref>{{cite web| url = https://www.aps.org/publications/apsnews/201902/weinberg.cfm| title = Q&A with Standard Bearer Steven Weinberg}}</ref>