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SOFTSUSY: a program for calculating supersymmetric spectra

B. C. Allanach

TL;DR

SOFTSUSY delivers a high-precision MSSM spectrum calculator with full flavour mixing, solving two-loop MSSM RGEs from a high-scale boundary to the electroweak scale and back, while enforcing radiative EWSB and incorporating comprehensive one- and two-loop corrections. The tool initializes from SM inputs, applies boundary conditions at a unification scale $M_X$, and iterates to convergence of the sparticle spectrum at $M_S$ with detailed treatment of threshold effects, CKM mixing, and Higgs sector radiative corrections expressed in the BPMZ framework. It supports full three-family Yukawa matrices and can operate in flavour-mixed or unmixed modes, with SLHA input/output and extensible interfaces for MSSM extensions and interface with collider and dark-mmatter computations. The resulting framework enables precise SUSY phenomenology, parameter extraction, and compatibility with event generators and related tools for collider and astrophysical studies, under a flexible, extensible C++ implementation.

Abstract

SOFTSUSY is a program which accurately calculates the spectrum of superparticles in the CP-conserving Minimal Supersymmetric Standard Model (MSSM), with a full flavour mixing structure. The program solves the renormalisation group equations with theoretical constraints on soft supersymmetry breaking terms provided by the user. Weak-scale gauge coupling and fermion mass data (including one-loop finite MSSM corrections) are used as a boundary condition, as well as successful radiative electroweak symmetry breaking. The program can also calculate a measure of fine-tuning. The program structure has been designed to easily generalise to extensions of the MSSM. This article serves as a self-contained guide to prospective users, and indicates the conventions and approximations used.

SOFTSUSY: a program for calculating supersymmetric spectra

TL;DR

SOFTSUSY delivers a high-precision MSSM spectrum calculator with full flavour mixing, solving two-loop MSSM RGEs from a high-scale boundary to the electroweak scale and back, while enforcing radiative EWSB and incorporating comprehensive one- and two-loop corrections. The tool initializes from SM inputs, applies boundary conditions at a unification scale , and iterates to convergence of the sparticle spectrum at with detailed treatment of threshold effects, CKM mixing, and Higgs sector radiative corrections expressed in the BPMZ framework. It supports full three-family Yukawa matrices and can operate in flavour-mixed or unmixed modes, with SLHA input/output and extensible interfaces for MSSM extensions and interface with collider and dark-mmatter computations. The resulting framework enables precise SUSY phenomenology, parameter extraction, and compatibility with event generators and related tools for collider and astrophysical studies, under a flexible, extensible C++ implementation.

Abstract

SOFTSUSY is a program which accurately calculates the spectrum of superparticles in the CP-conserving Minimal Supersymmetric Standard Model (MSSM), with a full flavour mixing structure. The program solves the renormalisation group equations with theoretical constraints on soft supersymmetry breaking terms provided by the user. Weak-scale gauge coupling and fermion mass data (including one-loop finite MSSM corrections) are used as a boundary condition, as well as successful radiative electroweak symmetry breaking. The program can also calculate a measure of fine-tuning. The program structure has been designed to easily generalise to extensions of the MSSM. This article serves as a self-contained guide to prospective users, and indicates the conventions and approximations used.

Paper Structure

This paper contains 32 sections, 38 equations, 2 figures, 14 tables.

Table of Contents

  1. Introduction
  2. The Nature of the Physical Problem
  3. The Program
  4. Aims and Layout
  5. MSSM Parameters
  6. Supersymmetric Parameters
  7. SUSY Breaking Parameters
  8. Tree-Level Masses
  9. Calculation
  10. Below $M_Z$
  11. Initial Estimate
  12. Gauge and Yukawa Couplings
  13. MSSM Renormalisation
  14. Electroweak Symmetry Breaking
  15. MSSM Spectrum
  16. ...and 17 more sections

Figures (2)

  • Figure 1: Iterative algorithm used to calculate the SUSY spectrum. Each step (represented by a box) is detailed in the text. The initial step is the uppermost one. $M_S$ is the scale at which the EWSB conditions are imposed, as discussed in the text. $M_X$ is the scale at which the high energy SUSY breaking boundary conditions are imposed.
  • Figure 2: Heuristic high-level object structure of SOFTSUSY. Inheritance is displayed by the lines.