Article

# Searching for Invisible and Almost Invisible Particles at e^+e^- Colliders

Physical Review Letters (Impact Factor: 7.73). 12/1995; 76(12). DOI: 10.1103/PhysRevLett.76.2002

Source: arXiv

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**ABSTRACT:**We show that in a general hidden sector model, supersymmetry breaking necessarily generates at one loop a scalar and gaugino mass as a consequence of the super-Weyl anomaly. We study a scenario in which this contribution dominates. We consider the Standard Model particles to be localized on a (3 + 1)-dimensional subspace or “3-brane” of a higher dimensional space-time, while supersymmetry breaking occurs off the 3-brane, either in the bulk or on another 3-brane. At least one extra dimension is assumed to be compactified roughly one to two orders of magnitude below the four-dimensional Planck scale. This framework is phenomenologically very attractive; it introduces new possibilities for solving the supersymmetric flavor problem, the gaugino mass problem, the supersymmetric CP problem, and the μ-problem. Furthermore, the compactification scale can be consistent with a unification of gauge and gravitational couplings. We demonstrate these claims in a four-dimensional effective theory below the compactification scale that incorporates the relevant features of the underlying higher dimensional theory and the contribution of the super-Weyl anomaly. Naturalness constraints follow not only from symmetries but also from the higher dimensional origins of the theory. We also introduce additional bulk contributions to the MSSM soft masses. This scenario is very predictive: the gaugino masses, squark masses, and A terms are given in terms of MSSM renormalization group functions.Nuclear Physics B 09/1999; · 4.33 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**A Weakly Interacting Massive Particle (WIMP) provides an attractive dark matter candidate, and should be within reach of the next generation of high-energy colliders. We consider the process of direct WIMP pair-production, accompanied by an initial-state radiation photon, in electron-positron collisions at the proposed International Linear Collider (ILC). We present a parametrization of the differential cross section for this process which conveniently separates the model-independent information provided by cosmology from the model-dependent inputs from particle physics. As an application, we consider two simple models, one supersymmetric, and another of the "universal extra dimensions" (UED) type. The discovery reach of the ILC and the expected precision of parameter measurements are studied in each model. In addition, for each of the two examples, we also investigate the ability of the ILC to distinguish between the two models through a shape-discrimination analysis of the photon energy spectrum. We show that with sufficient beam polarization the alternative model interpretation can be ruled out in a large part of the relevant parameter space. Comment: 21 pages, 9 figuresNew Journal of Physics 02/2009; · 4.06 Impact Factor - [Show abstract] [Hide abstract]

**ABSTRACT:**We consider, in the context of the minimal supersymmetric standard model, the case where the gravitino weighs 10^6 GeV or more, which is preferred by various cosmological difficulties associated with unstable gravitinos. Despite the large Higgs mixing parameter B together with the little hierarchy to other soft supersymmetry breaking masses, a light higgsino with an electroweak scale mass leads to successful electroweak symmetry breaking, at the price of fine-tuning the higgsino mixing mu parameter. Furthermore the light higgsinos produced at the decays of gravitinos can constitute the dark matter of the universe. The heavy squark mass spectrum of O(10^4) GeV can increase the Higgs boson mass to about 125 GeV or higher.Journal of High Energy Physics 12/2011; 2012(9). · 5.62 Impact Factor

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