Primary Feynman rules to calculate the epsilon-dimensional integrand of any 1-loop amplitude

TL;DR

This paper presents fundamental Feynman rules for extracting epsilon-dimensional rational contributions in 1-loop amplitudes within dimensional regularization, applicable to various theories including the Standard Model, QCD, and SUSY.

Contribution

It introduces a systematic set of rules to compute epsilon-dimensional integrand contributions at the integrand level for any theory with scalars, vectors, and fermions.

Findings

Provides a universal method for epsilon-dimensional integrand extraction.

Applicable to a wide range of quantum field theories.

Facilitates more accurate 1-loop amplitude calculations.

Abstract

When using dimensional regularization/reduction the epsilon-dimensional numerator of the 1-loop Feynman diagrams gives rise to rational contributions. I list the set of fundamental rules that allow the extraction of such terms at the integrand level in any theory containing scalars, vectors and fermions, such as the electroweak standard model, QCD and SUSY.