Showing papers on "Effective action published in 1979"
TL;DR: The time-dependent variational principle used in derivations of time dependent Hartree-Fock theory gives a variational definition for the effective action -the generating functional of single particle irreducible n -point functions as discussed by the authors.
159 citations
TL;DR: In this paper, the one-loop contributions of conformally invariant scalar fields to the effective action were calculated for homogeneous cosmological models with small anisotropy, and the dynamical equations which determine the classical geometry were displayed and the matrix elements of the stress energy tensor between the initial and final vacuums were determined.
Abstract: The one-loop contributions of conformally invariant scalar fields to the effective action are calculated for homogeneous cosmological models with small anisotropy. The dynamical equations which determine the classical geometry are displayed and the matrix elements of the stress-energy tensor between the initial and final vacuums are determined.
81 citations
TL;DR: In this paper, a systematic method of calculating the massless fermion propagation function and effective action in the background gauge field of an arbitrary number of widely separated instantons and anti-instantons was developed.
24 citations
TL;DR: In this article, an effective Lagrangian for the conformally coupled Klein-Gordon field in an expanding 3-flat Robertson-Walker universe is deduced, and from this the number density of the particle pairs created is calculated exactly.
Abstract: An effective Lagrangian for the conformally coupled Klein-Gordon field in an expanding 3-flat Robertson-Walker universe is deduced, and from this the number density of the particle pairs created is calculated exactly. An approximation formula for the imaginary part of the effective action density is given. It is applied to the already solved case and to an as yet not exactly solved one.
5 citations
TL;DR: In this article, it is shown that the functional integral technique yields an acceptable symmetry-breaking solution for static ultralocalgϕ4 theory, which coincides with one of the infinitely many solutions of the branching equations presented in a previous work.
Abstract: It is shown that, by using a suitable integration trajectory, the functional integral technique yields an acceptable symmetry-breaking solution for static ultralocalgϕ4 theory. This solution, which is present both in the case of a real bare mass and for an imaginary one, coincides with one of the infinitely many solutions of the branching equations presented in a previous work. It is proved in both cases that the solution corresponds to a minimum for the effective action, but that only for an imaginary bare mass a power series expansion which is equivalent to loop expansion gives a first term coinciding with the classical value of the field.
1 citations