Physics:Quantum chromodynamics - Revision history

WikiHarold: Remove imported red links from Quantum page

2026-05-23T23:46:54Z

Remove imported red links from Quantum page

← Older revision		Revision as of 23:46, 23 May 2026
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	<div style="flex:1; line-height:1.45; color:#006b45; column-count:2; column-gap:32px; column-rule:1px solid #b8d8c8;">		<div style="flex:1; line-height:1.45; color:#006b45; column-count:2; column-gap:32px; column-rule:1px solid #b8d8c8;">
	{{short description\|Theory of the strong nuclear interactions}}		{{short description\|Theory of the strong nuclear interactions}}
	~~{{Standard model of particle physics\|cTopic=quantum chromodynamics}}~~

	In theoretical physics, '''quantum chromodynamics''' ('''QCD''') is the theory of the strong interaction between quarks mediated by gluons. Quarks are fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD is a type of [[Physics:Quantum field theory\|quantum field theory]] called a non-abelian gauge theory, with symmetry group SU(3). The QCD analog of electric charge is a property called ''color''. Gluons are the force carriers of the theory, just as photons are for the electromagnetic force in [[Physics:Quantum electrodynamics\|quantum electrodynamics]]. The theory is an important part of the Standard Model of particle physics. A large body of [[Physics:Quantum chromodynamics#Experimental tests\|experimental evidence for QCD]] has been gathered over the years.		In theoretical physics, '''quantum chromodynamics''' ('''QCD''') is the theory of the strong interaction between quarks mediated by gluons. Quarks are fundamental particles that make up composite hadrons such as the proton, neutron and pion. QCD is a type of [[Physics:Quantum field theory\|quantum field theory]] called a non-abelian gauge theory, with symmetry group SU(3). The QCD analog of electric charge is a property called ''color''. Gluons are the force carriers of the theory, just as photons are for the electromagnetic force in [[Physics:Quantum electrodynamics\|quantum electrodynamics]]. The theory is an important part of the Standard Model of particle physics. A large body of [[Physics:Quantum chromodynamics#Experimental tests\|experimental evidence for QCD]] has been gathered over the years.

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	==History==		==History==
	~~{{main\|Physics:History of quantum mechanics\|Physics:History of quantum field theory}}~~
	With the invention of bubble chambers and spark chambers in the 1950s, experimental particle physics discovered a large and ever-growing number of particles called hadrons. It seemed that such a large number of particles could not all be fundamental. First, the particles were classified by charge and isospin by [[Biography:Eugene Wigner\|Eugene Wigner]] and [[Biography:Werner Heisenberg\|Werner Heisenberg]]; then, in 1953–56,<ref>		With the invention of bubble chambers and spark chambers in the 1950s, experimental particle physics discovered a large and ever-growing number of particles called hadrons. It seemed that such a large number of particles could not all be fundamental. First, the particles were classified by charge and isospin by [[Biography:Eugene Wigner\|Eugene Wigner]] and [[Biography:Werner Heisenberg\|Werner Heisenberg]]; then, in 1953–56,<ref>
	{{cite journal		{{cite journal
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	===Perturbative QCD===		===Perturbative QCD===
	~~{{main\|Physics:Perturbative QCD}}~~
	This approach is based on asymptotic freedom, which allows perturbation theory to be used accurately in experiments performed at very high energies. Although limited in scope, this approach has resulted in the most precise tests of QCD to date.		This approach is based on asymptotic freedom, which allows perturbation theory to be used accurately in experiments performed at very high energies. Although limited in scope, this approach has resulted in the most precise tests of QCD to date.

	===Lattice QCD===		===Lattice QCD===
	~~{{main\|Physics:Lattice QCD}}~~
	[[Image:Fluxtube meson.png\|right\|thumb\|150px\|{{langle}}''E''<sup>2</sup>{{rangle}} plot for static quark–antiquark system held at a fixed separation, where blue is zero and red is the highest value (result of a lattice QCD simulation by M. Cardoso et al.<ref>{{cite journal \|first1=M. \|last1=Cardoso \|first2=N. \|last2=Cardoso \|first3=P. \|last3=Bicudo \|display-authors=1 \|title=Lattice QCD computation of the colour fields for the static hybrid quark–gluon–antiquark system, and microscopic study of the Casimir scaling \|journal=Phys. Rev. D \|volume=81 \|issue= 3\|pages=034504 \|year=2010 \|doi=10.1103/PhysRevD.81.034504 \|arxiv=0912.3181 \|bibcode=2010PhRvD..81c4504C \|s2cid=119216789 }}</ref>)]]		[[Image:Fluxtube meson.png\|right\|thumb\|150px\|{{langle}}''E''<sup>2</sup>{{rangle}} plot for static quark–antiquark system held at a fixed separation, where blue is zero and red is the highest value (result of a lattice QCD simulation by M. Cardoso et al.<ref>{{cite journal \|first1=M. \|last1=Cardoso \|first2=N. \|last2=Cardoso \|first3=P. \|last3=Bicudo \|display-authors=1 \|title=Lattice QCD computation of the colour fields for the static hybrid quark–gluon–antiquark system, and microscopic study of the Casimir scaling \|journal=Phys. Rev. D \|volume=81 \|issue= 3\|pages=034504 \|year=2010 \|doi=10.1103/PhysRevD.81.034504 \|arxiv=0912.3181 \|bibcode=2010PhRvD..81c4504C \|s2cid=119216789 }}</ref>)]]
	Among non-perturbative approaches to QCD, the most well established is lattice QCD. This approach uses a discrete set of spacetime points (called the lattice) to reduce the analytically intractable path integrals of the continuum theory to a very difficult numerical computation that is then carried out on supercomputers like the QCDOC, which was constructed for precisely this purpose. While it is a slow and resource-intensive approach, it has wide applicability, giving insight into parts of the theory inaccessible by other means, in particular into the explicit forces acting between quarks and antiquarks in a meson. However, the numerical sign problem makes it difficult to use lattice methods to study QCD at high density and low temperature (e.g. nuclear matter or the interior of neutron stars).		Among non-perturbative approaches to QCD, the most well established is lattice QCD. This approach uses a discrete set of spacetime points (called the lattice) to reduce the analytically intractable path integrals of the continuum theory to a very difficult numerical computation that is then carried out on supercomputers like the QCDOC, which was constructed for precisely this purpose. While it is a slow and resource-intensive approach, it has wide applicability, giving insight into parts of the theory inaccessible by other means, in particular into the explicit forces acting between quarks and antiquarks in a meson. However, the numerical sign problem makes it difficult to use lattice methods to study QCD at high density and low temperature (e.g. nuclear matter or the interior of neutron stars).
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	===QCD sum rules===		===QCD sum rules===
	~~{{main\|Physics:QCD sum rules}}~~

	Based on an Operator product expansion one can derive sets of relations that connect different observables with each other.		Based on an Operator product expansion one can derive sets of relations that connect different observables with each other.

	==Experimental tests==<!-- This section is linked from [[Physics:Quantum chromodynamics\|Quantum chromodynamics]] -->		==Experimental tests==<!-- This section is linked from [[Physics:Quantum chromodynamics\|Quantum chromodynamics]] -->
	The notion of quark flavors was prompted by the necessity of explaining the properties of hadrons during the development of the quark model. The notion of color was necessitated by the puzzle of the ~~{{SubatomicParticle\|Delta++}}~~. This has been dealt with in the section on [[Physics:Quantum chromodynamics#History\|the history of QCD]].		The notion of quark flavors was prompted by the necessity of explaining the properties of hadrons during the development of the quark model. The notion of color was necessitated by the puzzle of the . This has been dealt with in the section on [[Physics:Quantum chromodynamics#History\|the history of QCD]].

	The first evidence for quarks as real constituent elements of hadrons was obtained in deep inelastic scattering experiments at SLAC. The first evidence for gluons came in three-jet events at PETRA.<ref>{{Cite journal \|last=Bethke \|first=S. \|date=2007-04-01 \|title=Experimental tests of asymptotic freedom \|url=https://www.sciencedirect.com/science/article/pii/S0146641006000615 \|journal=Progress in Particle and Nuclear Physics \|language=en \|volume=58 \|issue=2 \|pages=351–386 \|doi=10.1016/j.ppnp.2006.06.001 \|arxiv=hep-ex/0606035 \|bibcode=2007PrPNP..58..351B \|s2cid=14915298 \|issn=0146-6410}}</ref>		The first evidence for quarks as real constituent elements of hadrons was obtained in deep inelastic scattering experiments at SLAC. The first evidence for gluons came in three-jet events at PETRA.<ref>{{Cite journal \|last=Bethke \|first=S. \|date=2007-04-01 \|title=Experimental tests of asymptotic freedom \|url=https://www.sciencedirect.com/science/article/pii/S0146641006000615 \|journal=Progress in Particle and Nuclear Physics \|language=en \|volume=58 \|issue=2 \|pages=351–386 \|doi=10.1016/j.ppnp.2006.06.001 \|arxiv=hep-ex/0606035 \|bibcode=2007PrPNP..58..351B \|s2cid=14915298 \|issn=0146-6410}}</ref>
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	{{DEFAULTSORT:Quantum Chromodynamics}}		{{DEFAULTSORT:Quantum Chromodynamics}}
	~~[[Category:Quantum chromodynamics\| ]]~~
	~~[[Category:Quantum field theory]]~~

	{{Sourceattribution\|Quantum chromodynamics}}		{{Sourceattribution\|Quantum chromodynamics}}

WikiHarold: Clean Quantum page image and red links

2026-05-23T23:33:45Z

Clean Quantum page image and red links

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WikiHarold: Use Quantum See also index module

2026-05-23T22:21:02Z

Use Quantum See also index module

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 There is also a correspondence between confinement in QCD – the fact that the color field is only different from zero in the interior of hadrons – and the behaviour of the usual magnetic field in the theory of [[Physics:Type-II superconductor|type-II superconductor]]s: there the magnetism is confined to the interior of the [[Physics:Abrikosov vortex|Abrikosov flux-line lattice]],<ref>Mathematically, the flux-line lattices are described by [[Biography:Emil Artin|Emil Artin]]'s braid group, which is nonabelian, since one braid can wind around another one.</ref> i.e., the London penetration depth ''λ'' of that  theory is analogous to the confinement radius ''R<sub>c</sub>'' of  quantum chromodynamics. Mathematically, this correspondendence is supported by the second term, <math>\propto  g G^a_\mu \bar{\psi}_i \gamma^\mu T^a_{ij} \psi_j\,,</math> on the r.h.s. of the Lagrangian.
-==See also==
+== See also ==
-* For overviews:
+{{#invoke:PhysicsQC|tocHeadingAndList|Physics:Quantum basics/See also}}
 ==References==

Harold: Add missing image fallback to Quantum header

2026-05-17T22:32:57Z

Add missing image fallback to Quantum header

← Older revision		Revision as of 22:32, 17 May 2026
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	~~<!--~~ No ~~lead~~ image available ~~in existing page~~. ~~-->~~		[[File:File not found.png\|thumb\|280px\|No image available.]]
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Harold: Restore Quantum article header template

2026-05-17T21:51:49Z

Restore Quantum article header template

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 {{short description|Theory of the strong nuclear interactions}}
 {{Standard model of particle physics|cTopic=quantum chromodynamics}}
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 }}</ref>
 *[[Physics:Chiral symmetry breaking|Chiral symmetry breaking]], the [[Physics:Spontaneous symmetry breaking|spontaneous symmetry breaking]] of an important global symmetry of quarks, detailed below, with the result of generating masses for hadrons far above the masses of the quarks, and making pseudoscalar mesons exceptionally light.  [[Biography:Yoichiro Nambu|Yoichiro Nambu]] was awarded the 2008 Nobel Prize in Physics for elucidating the phenomenon, a dozen years before the advent of QCD.   Lattice simulations have confirmed all his generic predictions.
 ==Terminology==

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2024-02-05T09:42:54Z

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