Is the CNMSSM more credible than the CMSSM?

Abstract

With Bayesian statistics, we investigate the full parameter space of the constrained "next-to-minimal" supersymmetric Standard Model (CNMSSM) with naturalness priors, which were derived in a previous work. In the past, most Bayesian analyses of the CNMSSM ignored naturalness of the electroweak (EW) scale by making prejudicial assumptions for parameters defined at the EW scale. We test the CNMSSM against the CMSSM with Bayesian evidence, which, with naturalness priors, incorporates a penalty for fine-tuning of the EW scale. With the evidence, we measure credibility with respect to all measurements, including the EW scale and LHC direct searches. We find that the evidence in favor of the CNMSSM versus the CMSSM is "positive" to "strong" but that if one ignores the $μ$-problem, the evidence is "barely worth mentioning" to "positive." The $μ$-problem significantly influences our findings. Unless one considers the $μ$-problem, the evidence in favor of the CNMSSM versus the CMSSM is at best "positive," which is two grades below "very strong." We, furthermore, identify the most probable regions of the CMSSM and CNMSSM parameter spaces and examine prospects for future discovery at hadron colliders.