Resolving the Constrained Minimal and Next-to-Minimal Supersymmetric Standard Models

TL;DR

This work analyzes the constrained NMSSM under two-loop gauge coupling unification and universal soft SUSY breaking, comparing it to the constrained MSSM using a unified input/output framework. It finds the NMSSM spectrum is typically MSSM-like, except in regions with significant singlet mixing that can dilute Higgs couplings and yield observable singlet states, or in the deep MSSM limit where the singlet effectively decouples. The study emphasizes the role of the electroweak potential's structure, multiple minima, and fine-tuning, showing distinct regions with differing top-quark masses and Higgs phenomenology. Practically, it outlines how to distinguish the models experimentally, notably via singlet-diluted Higgs signatures and parity between MSSM-equivalent spectra, with LEP/LEP II sensitivities highlighted as crucial tests.

Abstract

We perform a detailed analysis of the next-to-minimal supersymmetric standard model (NMSSM), imposing the constraints of two-loop gauge coupling unification, universal soft supersymmetry breaking and the correct pattern of electroweak symmetry breaking. We compare our results with those for the minimal supersymmetric standard model (MSSM) using closely related techniques and, as far as possible, a common set of input and output variables. In general, in the constrained NMSSM, there are much stronger correlations between parameters than in the constrained MSSM, and we map out the allowed parameter space. We also give a detailed discussion of how to resolve the two models experimentally, concentrating primarily on the prospects at LEPII.