Neutralino Dark Matter in MSSM Models with Non-Universal Higgs Masses

We consider the Minimal Supersymmetric Standard Model (MSSM) with varying amounts of non-universality in the soft supersymmetry-breaking contributions to the Higgs scalar masses. In addition to the constrained MSSM (CMSSM) in which these are universal with the soft supersymmetry-breaking contributions to the squark and slepton masses at the input GUT scale, we consider scenarios in which both the Higgs masses are non-universal by the same amount (NUHM1), and scenarios in which they are independently non-universal (NUHM2). As the lightest neutralino is a dark matter candidate, we demand that the relic density of neutralinos not be in conflict with measurements by WMAP and others, and examine the viable regions of parameter space. Prospects for direct detection of neutralino dark matter via elastic scattering in these scenarios are discussed.Comment: 8 pages, 6 figures, to be published in the proceedings of the Invisible Universe International Conference, UNESCO, Paris, June 29 - July 3, 200

Dark Matter and EWSB Naturalness in Unified SUSY Models

The relationship between the degree of fine-tuning in Electroweak Symmetry Breaking (EWSB) and the discoverability of dark matter in current and next generation direct detection experiments is investigated in the context of two unified Supersymmetry scenarios: the constrained Minimal Supersymmetric Standard Model (CMSSM) and models with non-universal Higgs masses (NUHM). Attention is drawn to the mechanism(s) by which the relic abundance of neutralino dark matter is suppressed to cosmologically viable values. After a summary of Amsel, Freese, and Sandick (2011), results are updated to reflect current constraints, including the discovery of a new particle consistent with a Standard Model-like Higgs boson. We find that a Higgs mass of ~125 GeV excludes the least fine-tuned CMSSM points in our parameter space and that remaining viable models may be difficult to probe with next generation direct dark matter searches. Relatively low fine-tuning and good direct detection prospects are still possible in NUHM scenarios.Comment: 10 pages, 7 figures, to appear in the proceedings of CETUP* 2012. v2: reference adde

Well-Mixed Dark Matter and the Higgs

The breaking of electroweak symmetry through renormalization group flow in models that have MSSM spectra is found to produce "well-mixed" neutralino dark matter with a relic density consistent with the WMAP data and elastic scattering cross section with nuclei consistent with current limits from direct dark matter searches. These models predict a Higgs boson mass in the range (125-126) GeV. Well-mixed neutralino dark matter is predominantly bino-like, but has significant Higgsino and wino content, each with fractions of comparable size. With a ~1 TeV gluino mass and sizable neutralino-nucleon scattering cross sections, natural models will be fully tested by both the LHC and future dark matter direct detection experiments.Comment: 8 pages, 3 figures. V2: Substantial revisions, title change

Varying the Universality of Supersymmetry-Breaking Contributions to MSSM Higgs Boson Masses

We consider the minimal supersymmetric extension of the Standard Model (MSSM) with varying amounts of non-universality in the soft supersymmetry-breaking contributions to the Higgs scalar masses. In addition to the constrained MSSM (CMSSM) in which these are universal with the soft supersymmetry-breaking contributions to the squark and slepton masses at the input GUT scale, we consider scenarios in which both the Higgs scalar masses are non-universal by the same amount (NUHM1), and scenarios in which they are independently non-universal (NUHM2). We show how the NUHM1 scenarios generalize the (m_{1/2}, m_0) planes of the CMSSM by allowing either mu or m_A to take different (fixed) values and we also show how the NUHM1 scenarios are embedded as special cases of the more general NUHM2 scenarios. Generalizing from the CMSSM, we find regions of the NUHM1 parameter space that are excluded because the LSP is a selectron. We also find new regions where the neutralino relic density falls within the range preferred by astrophysical and cosmological measurements, thanks to rapid annihilation through direct-channel Higgs poles, or coannihilation with selectrons, or because the LSP composition crosses over from being mainly bino to mainly Higgsino. Generalizing further to the NUHM2, we find regions of its parameter space where a sneutrino is the LSP, and others where neutralino coannihilation with sneutrinos is important for the relic density. In both the NUHM1 and the NUHM2, there are slivers of parameter space where the LHC has fewer prospects for discovering sparticles than in the CMSSM, because either m_{1/2} and/or m_0 may be considerably larger than in the CMSSM.Comment: 39 pages, 16 figure