All-order Feynman rules for leading-twist gauge-invariant operators in QCD

Abstract

We present the Feynman rules for leading-twist gauge-invariant quark and gluon operators with an arbitrary number of total derivatives and applicable to any order in perturbation theory. This generalizes previous results and constitutes a necessary ingredient in the computation of the matrix elements of the corresponding operators. The results are written in a form appropriate for implementation in a computer algebra system. To illustrate the latter we provide implementations in Mathematica and FORM, which are made available at https://github.com/vtsam/NKLO.

Comments: 22 pages, LaTex, 9 figures, v2: major revision: conventions for quark operator rules changed and Feynman rules for gluon operators were added