Gauge Independence of the S-Matrix in the Causal Approach

TL;DR

This paper demonstrates that the physical S-matrix in Yang-Mills theories remains gauge-independent when analyzed through the causal Epstein-Glaser method combined with perturbative gauge invariance, providing a rigorous proof.

Contribution

It provides a simple inductive proof of the gauge independence of the S-matrix using the causal approach and perturbative gauge invariance.

Findings

Proves gauge independence of the S-matrix in Yang-Mills theories

Uses Epstein-Glaser causal method for analysis

Establishes gauge invariance through inductive reasoning

Abstract

The gauge dependence of the time-ordered products for Yang-Mills theories is analysed in perturbation theory by means of the causal method of Epstein and Glaser together with perturbative gauge invariance. This approach allows a simple inductive proof of the gauge independence of the physical S-matrix.