Catino, Francesca (2012) Supersymmetry-breaking vacua in simple and extended supergravity and flux compactifications. [Tesi di dottorato]
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The search for semi-realistic supergravity models, seen as the low-energy limit of superstring theory, strongly motivates the study of gauged supergravities and flux compactifications. Outstanding problems in this context are supersymmetry breaking, moduli stabilization and the generation of a small positive vacuum energy density. Whilst spontaneously broken N=1 supergravity is the only phenomenologically viable possibility in four dimensions, its vast arbitrariness is significantly reduced when considering consistent truncations of extended supergravities or, more generally, effective theories of flux compactifications. In this thesis we explore some aspects of supersymmetry breaking for which the constrained theoretical frameworks of extended supergravities and of flux compactifications play an important role. We begin by reviewing the basic structure of four-dimensional supergravities and of flux compactifications of the higher-dimensional ones. We then describe some original work on Fayet-Iliopoulos (FI) terms and de Sitter (dS) vacua: we introduce a novel distinction between genuine FI terms and impostors; we formulate a simple anomaly-free model with a genuine FI term, a classically stable dS vacuum and no global symmetries; we explore the relations between N=1 FI terms and their counterparts in extended supergravities, by discussing suitable truncations of the latter. We continue with other original work on the relation between M-theory compactifications with geometrical and non-geometrical fluxes, gauged N=8 supergravity in four dimensions and consistent N=1 truncations of the latter. In particular: we discuss the quadratic constraints on general fluxes in M-theory, relating them with the conditions on the embedding tensor that defines the gauged N=8 theory; we identify the fluxes generating four-parameter supersymmetry breaking à la Scherk-Schwarz, and comment on the one-loop stability of the resulting Minkowski background.
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La ricerca di modelli semi-realistici di supergravità, visti come limite di bassa energia delle teorie di superstring, motivano fortemente lo studio delle teorie di supergravità con gruppi di gauge non banali e delle compattificazioni con flussi.
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