Generating and Calculating One-loop Feynman Diagrams with FeynArts, FormCalc, and LoopTools

Abstract

A set of programs is presented for automatically generating and calculating Feynman diagrams. Diagrams are generated with FeynArts, then algebraically simplified using a combination of Mathematica and FORM implemented in the package FormCalc, and finally evaluated numerically using the LoopTools package. FormCalc works either in dimensional regularization or in constrained differential renormalization, the latter of which is equivalent at the one-loop level to regularization by dimensional reduction. FormCalc combines the speed of FORM with the powerful instruction set of Mathematica, and the latter greatly eases further processing of the results (e.g. selecting or modifying terms). The output is in a form well suited for numerical evaluation, which is then straightforward using the implementations of the one-loop integrals in LoopTools.