Faculty of Science
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Item Natural supersymmetry and dynamical flavour with meta-stable vacua(Springer, 2014-07-29) Abela, Steven; McGarrie, MoritzWe show how gauged flavour breaking and N = 1 supersymmetry breaking can be dynamically aligned to produce natural models. Supersymmetry is broken in a metastable vacuum, while a weakly gauged flavour symmetry is identified with an SU (3) F subgroup of the global symmetry of the SQCD model. We find that alignment can easily occur either through strongly coupled flavour models, with SQCD bound states playing the role of flavons, or entirely weakly coupled and renormalizable models with elementary SU (3) F adjoint flavons. In both cases it is essential that the SU (3) F breaking, and hence all the flavour structure, is driven dynamically by the SUSY breaking. The resulting flavour gauge mediation in conjunction with the usual gauge mediation contribution leads to naturally light third generations squarks, with first and second generations above.Item Light third-generation squarks from flavour gauge messengers(Springer, 2014-04-10) Brummer, Felix; McGarrie, Moritz; Weiler, AndreasWe study models of gauge-mediated supersymmetry breaking with a gauged horizontal SU(3)F symmetry acting on the quark superfields. If SU(3)F is broken nonsupersymmetrically by F -term vacuum expectation values, the massive gauge bosons and gauginos become messengers for SUSY breaking mediation. These gauge messenger fields induce a flavour-dependent, negative contribution to the soft masses of the squarks at one loop. In combination with the soft terms from standard gauge mediation, one obtains large and degenerate first- and second-generation squark masses, while the stops and sbottoms are light. We discuss the implications of this mechanism for the superparticle spectrum and for flavour precision observables. We also provide an explicit realization in a model with simultaneous SUSY and SU(3)F breaking.