Related papers: Abelian and Non-Abelian Dualities in String Bacgro…
We study a class of extremal transitions between topological distinct Calabi--Yau manifolds which have an interpretation in terms of the special massless states of a type II string compactification. In those cases where a dual heterotic…
We revisit non-Abelian T-duality for non-semisimple groups, where it is well-known that a mixed gravitational-gauge anomaly leads to $\sigma$-models that are scale, but not Weyl-invariant. Taking into account the variation of a non-local…
This PhD thesis investigates several aspects of nonabelian higher gauge theories, which appear in many areas of physics, notably string theory and gauged supergravity. We show that nonabelian higher gauge theory admits a consistent…
We show how to implement T-duality along non-abelian isometries in backgrounds with non-vanishing Ramond fields. When the dimension of the isometry group is odd (even) the duality swaps (preserves) the chirality of the theory. In certain…
We consider a class of $2+D$ - dimensional string backgrounds with a target space metric having a covariantly constant null Killing vector and flat `transverse' part. The corresponding sigma models are invariant under $D$ abelian isometries…
Duality symmetries in supergravity theories, together with their implications for string theory, are reviewed.
This work is devoted to a study of some of the non-perturbative aspects of superstring theory that have come within reach thanks to dualities. The first chapter gives a non-technical zero-equation introduction to these developments intended…
Noncommutative gauge fields (similar to the type that arises in string theory with background B-fields) are constructed for arbitrary nonabelian gauge groups with the help of a map that relates ordinary nonabelian and noncommutative gauge…
We consider the interplay of duality symmetries and gauged isometries of supergravity models giving N-extended, spontaneously broken supergravity with a no-scale structure. Some examples, motivated by superstring and M-theory…
We review the properties of static, higher dimensional black hole solutions in theories where non-abelian gauge fields are minimally coupled to gravity. It is shown that black holes with hyperspherically symmetric horizon topology do not…
We study the equivalence/duality between various non-commutative gauge models at the classical and quantum level. The duality is realised by a linear Seiberg-Witten-like map. The infinitesimal form of this map is analysed in more details.
We consider no-scale extended supergravity models as they arise from string and M-theory compactifications in presence of fluxes. The special role of gauging axion symmetries for the Higgs and superHiggs mechanism is outlined.
Supergravity solutions describing supersymmetric rotating bound states of NS fivebranes, fundamental strings and momentum can sometimes have an ergoregion but no horizon. In such supersymmetric ergoregions, there is an unusual feature that…
Potentially realistic string models often contain additional abelian gauge factors besides the standard model group. The consequences of such extended gauge structure are manifold both for theory and phenomenology as I show focussing in the…
We present a general discussion of strings propagating on noncompact coset spaces $G/H$ in terms of gauged WZW models, emphasizing the role played by isometries in the existence of target space duality. Fixed points of the gauged…
On compactification to six spacetime dimensions, the fundamental heterotic string admits as a soliton a dual string whose effective worldsheet action couples to the background fields of the dual formulation of six-dimensional supergravity.…
We consider an extension of a special class of conformal sigma models (`chiral null models') which describe extreme supersymmetric string solutions. The new models contain both `left' and `right' vector couplings and should correspond to…
We study the symmetry of the one-loop effective action of bosonic string theory under non-Abelian T-duality transformations. It is shown that the original Lagrangian and its dual are proportional. This result implies that the corresponding…
A general covariant quantization of superparticle, Green-Schwarz superstring and a supermembrane with manifest supersymmetry and duality symmetry is proposed. This quantization provides a natural quantum mechanical description of curved…
This is the content of a set of lectures given at the XIII Jorge Andre Swieca Summer School on Particles and Fields, held in Campos do Jordao, Brazil in January 2005. They intend to be a basic introduction to the topic of gauge/gravity…