Automatic Computation of Cross Sections in HEP

TL;DR

The paper presents GRACE, an automatic system for computing high-energy cross sections by automatically generating Feynman diagrams, producing numerical code, and performing Monte Carlo integration for tree-level and one-loop amplitudes. It covers system architecture, workflow, and extensions to the MSSM, along with validation via gauge-invariance checks and non-linear gauge methods. The authors highlight substantial physics achievements, including numerous multi-particle final states and SUSY processes, and discuss computational challenges such as parallelization, singular integrals, symbolic manipulation, and high-precision arithmetic. These contributions show GRACE as a practical tool for generating theoretical predictions across current and future accelerator experiments. The work also outlines ongoing improvements needed to scale to even larger and more complex processes.

Abstract

For the study of reactions in High Energy Physics (HEP) automatic computation systems have been developed and are widely used nowadays. GRACE is one of such systems and it has achieved much success in analyzing experimental data. Since we deal with the cross section whose value can be given by calculating hundreds of Feynman diagrams, we manage the large scale calculation, so that effective symbolic manipulation, the treat of singularity in the numerical integration are required. The talk will describe the software design of GRACE system and computational techniques in the GRACE.