GRACE/SUSY Automatic Generation of Tree Amplitudes in the Minimal Supersymmetric Standard Model

TL;DR

GRACE/SUSY automates the generation of tree‑level MSSM amplitudes and cross sections, extending GRACE with MSSM vertices, Majorana handling, and a generalized Higgs potential. The framework maps MSSM parameters to two input schemes and a G‑line formalism for fermion‑number clashing, enabling end‑to‑end computation from model definition to event generation via BASES/SPRING. It provides detailed user workflows, from process definition to graph drawing, source‑code generation, gauge checks, integration, and event production, while offering extensive validation against established tools. The work enables efficient, automated SUSY process simulations at tree level, with potential extensions to loop calculations, R‑parity violation, and RGE‑improved inputs, facilitating phenomenological studies at current and future colliders.

Abstract

GRACE/SUSY is a program package for generating the tree-level amplitude and evaluating the corresponding cross section of processes of the minimal supersymmetric extension of the standard model (MSSM). The Higgs potential adopted in the system, however, is assumed to have a more general form indicated by the two-Higgs-doublet model. This system is an extension of GRACE for the standard model(SM) of the electroweak and strong interactions. For a given MSSM process the Feynman graphs and amplitudes at tree-level are automatically created. The Monte-Carlo phase space integration by means of BASES gives the total and differential cross sections. When combined with SPRING, an event generator, the program package provides us with the simulation of the SUSY particle productions.

Figures (2)

• Figure 1: Feynman graphs for $e^+e^-$$\to$$\gamma\tilde{\chi_1^+}\tilde{\chi_1^-}$ in the MSSM.
• Figure 2: Relation among the program components.