Related papers: Non-Supersymmetric Open String Vacua
We present a detailed analysis of non-supersymmetric spacetime varying string vacua which can lead to an exponential hierarchy between the electroweak and the gravitational scales. In particular, we identify a limit in which these vacua can…
We present a construction of a perturbatively stable non-supersymmetric type II closed string model in four dimensions. It is based on a freely acting Scherk-Schwarz Z2-deformation of a supersymmetric construction which is recovered in…
We present a string theory construction in which the particle physics contributions to the one-loop vacuum energy exactly cancel, whilst the gravitational contributions are suppressed in the size of one or two large extra dimensions. This…
We study de Sitter configurations in ten-dimensional string models where supersymmetry is either absent or broken at the string scale. To this end, we derive expressions for the cosmological constant in general warped flux compactifications…
We construct supersymmetric $\mathrm{AdS}_4$ vacua of type IIB string theory in compactifications on orientifolds of Calabi-Yau threefold hypersurfaces. We first find explicit orientifolds and quantized fluxes for which the superpotential…
We investigate mechanisms that can trigger supersymmetry breaking in open string vacua. The focus is on backgrounds with D-branes and orientifold planes that have an exact string description, and allow to study some of the quantum effects…
It is well-known that Scherk-Schwarz compactifications in string theory have a tachyon in the closed string spectrum appearing for a critical value of a compact radius. The tachyon can be removed by an appropriate orientifold projection in…
In this Thesis we investigate properties of stability, rigidity and unitarity of the string landscape in ten and lower dimensions. The dissertation explores these aspects by intertwining a detailed analysis of string vacua, with and without…
We study supersymmetry breaking by Scherk-Schwarz compactifications in type I string theory. While in the gravitational sector all mass splittings are proportional to a (large) compactification radius, supersymmetry remains unbroken for the…
A new framework is found for the compactification of supersymmetric string theory. It is shown that the massless spectra of Calabi--Yau manifolds of complex dimension $D_{crit}$ can be derived from noncritical manifolds of complex dimension…
We present a dual formulation of the construction of N=2 nonlinear sigma-model type conformal field theories with c=9 which are mainly used as internal sectors of Calabi-Yau heterotic string compactifications. The supercurrents and the…
We consider massive type IIA compactifications down to 4 dimensions in presence of O6 planes and D6 branes parallel to them, in order to preserve half-maximal supersymmetry in 4D. The dynamics of open strings living on the spacetime filling…
In this note we construct large ensembles of supersymmetry breaking solutions arising in the context of flux compactifications of type IIB string theory. This class of solutions was previously proposed in arXiv:hep-th/0402135 for which we…
Following Kachru, Kumar and Silverstein, we construct a set of non-supersymmetric Type II string models which have equal numbers of bosons and fermions at each mass level. The models are asymmetric {\bf Z}_2 \otimes {\bf Z}_2^{\prime}…
We consider known examples of non-supersymmetric AdS$_7$ and AdS$_4$ solutions arising from compactifications of massive type IIA supergravity and study their stability, taking into account the coupling between closed- and open-string…
In a recent paper [1] we showed that N=1 supersymmetric QCD in the presence of certain superpotential deformations has a rich landscape of supersymmetric and non-supersymmetric vacua. In this paper we embed this theory in string theory as a…
We construct N=1 and N=0 chiral four-dimensional vacua of flux compactification in Type IIB string theory. These vacua have the common features that they are free of tadpole instabilities (both NSNS and RR) even for models with N=0…
The space of four dimensional string and $M$ theory vacua with non-Abelian gauge symmetry, chiral fermions and unbroken supersymmetry beyond the electroweak scale appears to be a disconnected space whose different components represent…
A way to break supersymmetry in perturbative superstring theory is the string version of the Scherk-Schwarz mechanism. There, the fermions and bosons have mass splitting due to different compactification boundary conditions. We consider the…
We consider the 1-loop effective potential in type I string theory compactified on a torus, with supersymmetry broken by the Scherk-Schwarz mechanism. At fixed supersymmetry breaking scale M, and up to exponentially suppressed terms, we…