Editing Tadpole (physics)

{{Short description|Type of Feynman diagram}}
In [[quantum field theory]], a '''tadpole''' is a one-loop [[Feynman diagram]] with one external leg, giving a contribution to a one-point [[correlation function (quantum field theory)|correlation function]] (i.e., the field's [[vacuum expectation value]]). One-loop diagrams with a [[propagator]] that connects back to its originating vertex are often also referred as tadpoles. For many massless theories, these graphs vanish in [[dimensional regularization]] (by [[dimensional analysis]] and the absence of any inherent [[energy scale|mass scale]] in the [[loop integral]]).
Tadpole corrections are needed if the corresponding external field has a non-zero vacuum expectation value, such as the [[Higgs field]].<ref>{{cite web |last1=Evans |first1=Tim |title='Diagramology' Types of Feynman Diagram |url=https://www.imperial.ac.uk/media/imperial-college/research-centres-and-groups/theoretical-physics/msc/current/qft/handouts/qftdiagramtypes.pdf}}</ref><br />
[[Image:tadpole.png]]

Tadpole diagrams were first used in the 1960s. An early example was published by [[Abdus Salam]] in 1961, though he did not take credit for the name.<ref>{{cite journal
 | author=[[Abdus Salam]]
 | year=1961
 | title=Some Speculations on the New Resonances
 | journal=[[Reviews of Modern Physics]]
 | volume=33| issue=3 |pages= 426–430
 | doi=10.1103/RevModPhys.33.426| bibcode=1961RvMP...33..426S
 }}</ref> Physicists [[Sidney Coleman]] and [[Sheldon Glashow]] made an influential use of tadpole diagrams to explain [[Spontaneous symmetry breaking|symmetry breaking]] in the [[strong interaction]] in 1964.
<ref>{{cite journal
 |author=[[Sidney Coleman|S. Coleman]], [[Sheldon Glashow|S. L. Glashow]]
 |year=1964
 |title=Departures from the Eightfold Way: Theory of Strong Interaction Symmetry Breakdown
 |journal=[[Physical Review]]
 |volume=134 |issue=3B|pages= B671–B681
 |doi=10.1103/PhysRev.134.B671
|bibcode = 1964PhRv..134..671C }}</ref>
<ref>{{cite news |last1=Flexi |first1=Mike |title=Quantum Physics |url=https://www.youtube.com/watch?v=O4LCEQxXK08 |access-date=26 July 2022}}</ref>
In 1985 Coleman stated (perhaps as a joke) that ''[[Physical Review]]''’s editors rejected the originally proposed name "spermion".<ref>{{Cite arXiv |last=Coleman |first=Sidney |date=2013-02-21 |title=Notes from Sidney Coleman's Physics 253a |class=physics.ed-ph |eprint=1110.5013}}</ref><ref>{{Citation |last1=Lancaster |first1=Tom |title=Statistical field theory |date=2014-04-17 |url=http://dx.doi.org/10.1093/acprof:oso/9780199699322.003.0026 |work=Quantum Field Theory for the Gifted Amateur |pages=190 |publisher=Oxford University Press |isbn=978-0-19-969932-2 |access-date=2022-04-19 |last2=Blundell |first2=Stephen J.|doi=10.1093/acprof:oso/9780199699322.003.0026 |url-access=subscription }}</ref>

== References ==
{{Reflist}}

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[[Category:Quantum field theory]]


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