Editing Effective field theory (section)

{{short description|Type of approximation to an underlying physical theory}}
{{More footnotes|date=May 2013}}
{{Quantum field theory|cTopic=Some models}}
{{merge to|Effective theory|discuss=Talk:Effective theory#Merge proposal|date=November 2024}}

In [[physics]], an '''effective field theory''' is a type of approximation, or [[effective theory]], for an underlying physical theory, such as a [[quantum field theory]] or a [[statistical mechanics]] model. An effective field theory includes the appropriate [[degrees of freedom (physics and chemistry)|degrees of freedom]] to describe physical phenomena occurring at a chosen [[length scale]] or energy scale, while ignoring substructure and degrees of freedom at shorter distances (or, equivalently, at higher energies). Intuitively, one averages over the behavior of the underlying theory at shorter length scales to derive what is hoped to be a simplified model at longer length scales. Effective field theories typically work best when there is a large separation between length scale of interest and the length scale of the underlying dynamics. Effective field theories have found use in [[particle physics]], [[statistical mechanics]], [[condensed matter physics]], [[general relativity]], and [[hydrodynamics]]. They simplify calculations, and allow treatment of [[Dissipative system|dissipation]] and [[radiation]] effects.<ref>{{Cite journal|doi=10.1103/PhysRevLett.110.174301|pmid=23679733|title=Classical Mechanics of Nonconservative Systems|journal=Physical Review Letters|volume=110|issue=17|pages=174301|year=2013|last1=Galley|first1=Chad R.|arxiv=1210.2745|bibcode=2013PhRvL.110q4301G|s2cid=14591873|doi-access=free}}</ref><ref>{{Cite journal |arxiv = 1402.2610|last1 = Birnholtz|first1 = Ofek|title = Radiation reaction at the level of the action|journal = International Journal of Modern Physics A|volume = 29|issue = 24|pages = 1450132–1450190|last2 = Hadar|first2 = Shahar|last3 = Kol|first3 = Barak|year = 2014|doi = 10.1142/S0217751X14501322|bibcode = 2014IJMPA..2950132B|s2cid = 118541484}}</ref>