Composite field

{{Short description|Field composed from other elementary fields}} {{See also|Composite field (mathematics)}} {{More citations needed|date=June 2025}}

In quantum field theory, a '''composite field''' is a field defined in terms of other more "elementary" fields. It might describe a composite particle (bound state) or it might not.

It might be local, or it might be nonlocal. However, "quantum fields do not exist as a point taken in isolation," so "local" does not mean literally a single point.<ref>{{cite book|url=https://books.google.com/books?id=lvT1CAAAQBAJ&dq=%22Composite+field%22+-wikipedia&pg=PA379|pages=379, 381|title=General Principles of Quantum Field Theory|year=2012|isbn=9789400904910|publisher=Springer Netherlands|access-date=June 12, 2025}}</ref>

Composite fields use a very specific kind of statistics, called "duality and arbitrary statistics".<ref>{{cite book|pages=175–178|url=https://books.google.com/books?id=fD41DwAAQBAJ&dq=%22Composite+field%22+-wikipedia&pg=PA176|title=Quantum Field Theory Approach to Condensed Matter Physics|first=Eduardo C. |last=Marino|year=2017|isbn=9781108508858|publisher=Cambridge University Press |access-date=June 12, 2025}}</ref>

Under Noether's theorem, Noether fields are often composite fields,<ref>{{cite book|url=https://books.google.com/books?id=MuH0TQvpY5sC&dq=Composite+field+noether+-wikipedia&pg=PA430|pages=430–431|title=The Conceptual Framework of Quantum Field Theory|first=Anthony |last=Duncan|year=2012|isbn=9780199573264|publisher=Oxford University Press|access-date=June 12, 2025}}</ref> and they are local.

In the generalized LSZ formalism, composite fields, which are usually nonlocal, are used to model asymptotic bound states.{{citation needed|date=June 2025}}

==References== {{reflist}}

Category:Quantum field theory