Next-to-Minimal SOFTSUSY

Abstract

We describe an extension to the SOFTSUSY program that provides for the calculation of the sparticle spectrum in the Next-to-Minimal Supersymmetric Standard Model (NMSSM), where a chiral superfield that is a singlet of the Standard Model gauge group is added to the Minimal Supersymmetric Standard Model (MSSM) fields. Often, a ${\mathbb{Z}}_3$ symmetry is imposed upon the model. SOFTSUSY can calculate the spectrum in this case as well as the case where general ${\mathbb{Z}}_3$ violating (denoted as $\backslash {\mathbb{Z}}_3$) terms are added to the soft supersymmetry breaking terms and the superpotential. The user provides a theoretical boundary condition for the couplings and mass terms of the singlet. Radiative electroweak symmetry breaking data along with electroweak and CKM matrix data are used as weak-scale boundary conditions. The renormalisation group equations are solved numerically between the weak scale and a high energy scale using a nested iterative algorithm. This paper serves as a manual to the NMSSM mode of the program, detailing the approximations and conventions used.

Comments: 23 pages, 2 figures, v6: corrected errors in the one- and two-loop beta functions of the ${\xi }_S$ parameter of the NMSSM (eqs. (D.48) and (D.49)). Source code can be obtained from http://softsusy.hepforge.org/