In this Snowmass whitepaper, we describe the impact of ongoing and proposed intensity frontier experiments on the parameter space of the Minimally Supersymmetric Standard Model (MSSM). We extend a set of phenomenological MSSM (pMSSM) models to includ
e non-zero CP-violating phases and study the sensitivity of various flavor observables in these scenarios Future electric dipole moment and rare meson decay experiments can have a strong impact on the viability of these models that is relatively independent of the detailed superpartner spectrum. In particular, we find that these experiments have the potential to probe models that are expected to escape searches at the high-luminosity LHC.
We present several benchmark points in the phenomenological Minimal Supersymmetric Standard Model (pMSSM). We select these models as experimentally well-motivated examples of the MSSM which predict the observed Higgs mass and dark matter relic densit
y while evading the current LHC searches. We also use benchmarks to generate spokes in parameter space by scaling the mass parameters in a manner which keeps the Higgs mass and relic density approximately constant.
We further examine the capability of the 7 and 8 TeV LHC to explore the parameter space of the p(henomenological)MSSM with neutralino LSPs. Here we present an updated study employing all of the relevant ATLAS SUSY analyses, as well as all relevant LH
C non-MET searches, whose data were publically available as of mid-September 2012. We find that roughly 1/3 of our pMSSM model points are excluded at present with an important role being played by both the heavy flavor and multi-lepton searches, as well as those for heavy stable charged particles. Nonetheless, we find that light gluinos, 1st/2nd generation squarks, and stop/sbottoms (lsim 400-700 GeV), as well as models with 1% fine-tuning or better, are still viable in the pMSSM. In addition, we see that increased luminosity at 8 TeV is unlikely to significantly improve the reach of the vanilla searches. The impact of these null searches on the SUSY sparticle spectrum is discussed in detail and the implications of these results for models with low fine-tuning, a future lepton collider and dark matter searches are examined.
The recent discovery of a 125 GeV Higgs, as well as the lack of any positive findings in searches for supersymmetry, has renewed interest in both the supersymmetric Higgs sector and fine-tuning. Here, we continue our study of the phenomenological MSS
M (pMSSM), discussing the light Higgs and fine-tuning within the context of two sets of previously generated pMSSM models. We find an abundance of models with experimentally-favored Higgs masses and couplings. We investigate the decay modes of the light Higgs in these models, finding strong correlations between many final states. We then examine the degree of fine-tuning, considering contributions from each of the pMSSM parameters at up to next-to-leading-log order. In particular, we examine the fine-tuning implications for our model sets that arise from the discovery of a 125 GeV Higgs. Finally, we investigate a small subset of models with low fine-tuning and a light Higgs near 125 GeV, describing the common features of such models. We generically find a light stop and bottom with complex decay patterns into a set of light electroweak gauginos, which will make their discovery more challenging and may require novel search techniques.
The pMSSM provides a broad perspective on SUSY phenomenology. In this paper we generate two new, very large, sets of pMSSM models with sparticle masses extending up to 4 TeV, where the lightest supersymmetric particle (LSP) is either a neutralino or
gravitino. The existence of a gravitino LSP necessitates a detailed study of its cosmological effects and we find that Big Bang Nucleosynthesis places strong constraints on this scenario. Both sets are subjected to a global set of theoretical, observational and experimental constraints resulting in a sample of sim 225k viable models for each LSP type. The characteristics of these two model sets are briefly compared. We confront the neutralino LSP model set with searches for SUSY at the 7 TeV LHC using both the missing (MET) and non-missing ET ATLAS analyses. In the MET case, we employ Monte Carlo estimates of the ratios of the SM backgrounds at 7 and 8 TeV to rescale the 7 TeV data-driven ATLAS backgrounds to 8 TeV. This allows us to determine the pMSSM parameter space coverage for this collision energy. We find that an integrated luminosity of sim 5-20 fb^{-1} at 8 TeV would yield a substantial increase in this coverage compared to that at 7 TeV and can probe roughly half of the model set. If the pMSSM is not discovered during the 8 TeV run, then our model set will be essentially void of gluinos and lightest first and second generation squarks that are lesssim 700-800 GeV, which is much less than the analogous mSUGRA bound. Finally, we demonstrate that non-MET SUSY searches continue to play an important role in exploring the pMSSM parameter space. These two pMSSM model sets can be used as the basis for investigations for years to come.
