XENON100 implications for naturalness in the MSSM, NMSSM, and λ-supersymmetry model

In a recent paper [M. Perelstein and B. Shakya, J. High Energy Phys. 10 (2011) 142.], we discuss the correlation between the elastic neutralino-nucleon scattering cross section constrained by dark matter direct-detection experiments and fine-tuning at tree level in the electroweak symmetry breaking sector of the minimal supersymmetric Standard Model (MSSM). Here, we show that the correlation persists in the next-to-minimal supersymmetric Standard Model (NMSSM), and its variant, the lambda-supersymmetry (SUSY) model. Both models are strongly motivated by the recent discovery of a 125 GeV Higgs-like particle. We also discuss the implications of the recently published bound on the direct-detection cross section from 225 live days of the XENON100 experiment. In both the MSSM and the NMSSM, most of the parameter space with fine-tuning less than 10% is inconsistent with the XENON100 bound. In the lambda-SUSY model, on the other hand, large regions of completely natural electroweak symmetry breaking are still allowed, primarily due to a parametric suppression of fine-tuning with large lambda. The upcoming XENON1T experiment will be able to probe most of the parameter space with less than 1% fine-tuning in all three models.