nLab
effective action functional

Idea

In the context of quantum field theory an effective action is an object obtained from a more fundamental action functional by “averaging out” the dependency on certain variables.

There are two different notions of effective action

1. The one-particle irreducible action (“1PI action”);

2. The Wilsonian effective action of effective quantum field theory.

1PI action

(…)

Wilsonian effective action

(…)

References

A discussion (with an eye towards supersymmetric quantum field theory and Seiberg duality) is in section 2.1 of

• Flip Tanedo, Notes on Seibergology (pdf)

A review of effective actions in the background field formalism is in section 3.1 of

• Darren Trevor Grasso, Higher order contributions to the effective action of $𝒩=2$ and $4$ supersymmetric Yang-Mills theories from heat kernel techniques in superspace Thesis (2007) (web)