Generating Functional for Connected Green’s Functions and the Effective Action (1PI Diagrams)

2019 ◽  
pp. 150-159
Symmetry ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 1985
Author(s):  
Pavel Yu. Moshin ◽  
Alexander A. Reshetnyak

A joint introduction of composite and background fields into non-Abelian quantum gauge theories is suggested based on the symmetries of the generating functional of Green’s functions, with the systematic analysis focused on quantum Yang–Mills theories, including the properties of the generating functional of vertex Green’s functions (effective action). For the effective action in such theories, gauge dependence is found in terms of a nilpotent operator with composite and background fields, and on-shell independence from gauge fixing is established. The basic concept of a joint introduction of composite and background fields into non-Abelian gauge theories is extended to the Volovich–Katanaev model of two-dimensional gravity with dynamical torsion, as well as to the Gribov–Zwanziger theory.


2012 ◽  
Vol 27 (22) ◽  
pp. 1250132 ◽  
Author(s):  
PETER M. LAVROV

We study a dependence of Green's functions for the Curci–Ferrari model on the parameter resembling the gauge parameter in massless Yang–Mills theories. It is shown that the on-shell generating functional of vertex functions (effective action) depends on this parameter.


1991 ◽  
Vol 06 (26) ◽  
pp. 2443-2452 ◽  
Author(s):  
V. P. GUSYNIN ◽  
V. A. MIRANSKY

An approach to the low energy effective action based on the formalism of Green's functions of composite is developed in field theories with dynamical symmetry breaking. The effective action of the gauged Nambu-Jona-Lasinio model is derived as a series in powers of the derivatives of composite fields. The mechanism of scale symmetry breaking in this model is discussed.


1987 ◽  
Vol 02 (03) ◽  
pp. 785-796 ◽  
Author(s):  
D. G. C. McKEON ◽  
T. N. SHERRY

Operator regularization is introduced as a procedure to compute Green's functions perturbatively. At the one-loop level the effective action is regularized by means of the ζ-function. A perturbative expansion due to Schwinger allows one to compute from the ζ-function one-loop one-particle irreducible Green's functions. By regulating in this way, we do not have to compute Feynman diagrams, we avoid having to introduce a regulating parameter into the initial Lagrangian and we do not encounter any divergent integrals. This procedure is illustrated for N = 1 super Yang-Mills theory in which the one-loop one-particle irreducible Green's function associated with the decay of the supercurrent into a vector and a spinor particle is treated. Gauge invariance is automatically maintained and the usual anomaly in the divergence of the super-current is recovered.


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