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This article first reviews the calculation of the N = 1 effective action for generic type IIA and type IIB Calabi-Yau orientifolds in the presence of background fluxes by using a Kaluza-Klein reduction. The Kähler potential, the gauge kinetic functions and the flux-induced superpotential are determined in terms of geometrical data of the Calabi-Yau(More)
We study the vacuum structure of compactifications of type II string theories on orientifolds with SU(3) × SU(3) structure. We argue that generalised geometry enables us to treat these non-geometric compactifications using a supergravity analysis in a way very similar to geometric compactifications. We find supersymmetric Minkowski vacua with all the moduli(More)
We study perturbative aspects of noncommutative field theories. This work is arranged in two parts. First, we review noncommutative field theories in general and discuss both canonical and path integral quantization methods. In the second part, we consider the particular example of noncommutative Φ4 theory in four dimensions and work out the corresponding(More)
In this paper we study a possible non-perturbative dual of the heterotic string compactified on K3× T 2 in the presence of background fluxes. We show that type IIA string theory compactified on manifolds with SU(3) structure can account for a subset of the possible heterotic fluxes. This extends our previous analysis to a case of a non-perturbative duality(More)
In this paper, we continue the analysis of heterotic string compactifications on half-flat mirror manifolds by including the 10-dimensional gauge fields. It is argued, that the heterotic Bianchi identity is solved by a variant of the standard embedding. Then, the resulting gauge group in four dimensions is still E6 despite the fact that the Levi-Civita(More)
In this review article we study type IIB superstring compactifications in the presence of space-time filling D-branes while preserving N = 1 supersymmetry in the effective four-dimensional theory. This amount of unbroken supersymmetry and the requirement to fulfill the consistency conditions imposed by the space-time filling D-branes lead to Calabi-Yau(More)
Recently, a lot of attention was devoted to the study of compactifications on manifolds with reduced structure group. Such manifolds usually appear when one considers generalized compactifications in the presence of non-trivial fluxes. It is well-known that purely geometrical compactifications are supersymmetric if the internal manifold admits a covariantly(More)
We study M-theory compactified on a specific class of seven-dimensional manifolds with SU(3) structure. The manifolds can be viewed as a fibration of an arbitrary Calabi-Yau threefold over a circle, with a U-duality twist around the circle. In some cases we find that in the four dimensional low energy effective theory a (broken) non-Abelian gauge group(More)
We study perturbative aspects of noncommutative field theories. This work is arranged in two parts. First, we review noncommutative field theories in general and discuss both canonical and path integral quantization methods. In the second part, we consider the particular example of noncommutative Φ4 theory in four dimensions and work out the corresponding(More)