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Register a new userFlavour Violation in Gauge-Mediated Supersymmetry Breaking Models: Experimental Constraints and Phenomenology at the LHC
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B. Fuks
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We present an extensive analysis of gauge-mediated supersymmetry breaking models with minimal and non-minimal flavour violation. We first demonstrate that low-energy, precision electroweak, and cosmological constraints exclude large collider-friendly regions of the minimal parameter space. We then discuss various possibilities how flavour violation, although naturally suppressed, may still occur in gauge-mediation models. The introduction of non-minimal flavour violation at the electroweak scale is shown to relax the stringent experimental constraints, so that benchmark points, that are also cosmologically viable, can be defined and their phenomenology, i.e. squark and gaugino production cross sections with flavour violation, at the LHC can be studied.
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We study squark flavour violation in the anomaly mediated supersymmetry broken (AMSB) minimal supersymmetric standard model. Analytical expressions for the three-generational squark mass matrices are derived. We show that the anomaly-induced soft breaking terms have a decreasing amount of squark flavour violation when running from the GUT to the weak scale. Taking into account inter-generational squark mixing, we work out non-trivial constraints from B -> Xs gamma and Bs -> mu mu, which complement each other, as well as B -> tau nu decays. We further identify a region of parameter space where the anomalous magnetic moment of the muon and the B -> Xs gamma branching ratio are simultaneously accommodated. Since anomaly mediation is of the minimal flavour-violating type, the generic flavour predictions for this class of models apply, including a CKM-induced (and hence small) Bs-Bsbar-mixing phase.
We investigate multilepton LHC signals arising from electroweak processes involving sleptons. We consider the framework of general gauge mediated supersymmetry breaking, focusing on models where the low mass region of the superpartner spectrum consists of the three generations of charged sleptons and the nearly massless gravitino. We demonstrate how such models can provide an explanation for the anomalous four lepton events recently observed by the CMS collaboration, while satisfying other existing experimental constraints. The best fit to the CMS data is obtained for a selectron/smuon mass of around 145 GeV and a stau mass of around 90 GeV. These models also give rise to final states with more than four leptons, offering alternative channels in which they can be probed and we estimate the corresponding production rates at the LHC.
We review the motivation for Gauge-Mediated Supersymmetry Breaking and discuss some recent advances.
We introduce new mechanisms for the communication of supersymmetry breaking via gauge interactions. These models do not require complicated dynamics to induce a nonvanishing F term for a singlet. The first class of models communicates supersymmetry breaking to the visible sector through a ``mediator field that transforms under both a messenger gauge group of the dynamical supersymmetry breaking sector and the standard model gauge group. This model has distinctive phenomenology; in particular, the scalar superpartners should be heavier by at least an order of magnitude than the gaugino superpartners. The second class of models has phenomenology more similar to the ``standard messenger sectors. A singlet is incorporated, but the model does not require complicated mechanisms to generate a singlet F term. The role of the singlet is to couple fields from the dynamical symmetry breaking sector to fields transforming under the standard model gauge group. We also mention a potential solution to the $mu$ problem.
We discuss the possibility of finding scenarios, within type IIB string theory compactified on Calabi-Yau orientifolds with fluxes, for realizing gauge mediated supersymmetry breaking. We find that while in principle such scenarios are not ruled out, in practice it is hard to get acceptable constructions, since typically, supersymmetry breaking cannot be separated from the stabilization of the light modulus.
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