Ulrich Theis - Academia.edu (original) (raw)

Papers by Ulrich Theis

Classical and Quantum Gravity, 2000

We construct non-standard interactions between exterior form gauge fields by gauging a particular... more We construct non-standard interactions between exterior form gauge fields by gauging a particular global symmetry of the Einstein-Maxwell action for such fields. Furthermore we discuss generalizations of such interactions by adding couplings to gravitational Chern-Simons forms and to fields arising through dimensional reduction. The construction uses an appropriate tensor calculus.

Nuclear Physics B, 1999

We construct N = 1 supersymmetric versions of four-dimensional Freedman-Townsend models and gener... more We construct N = 1 supersymmetric versions of four-dimensional Freedman-Townsend models and generalizations thereof found recently by Henneaux and Knaepen, with couplings between 1-form and 2-form gauge potentials. The models are presented both in a superfield formulation with linearly realized supersymmetry and in WZ gauged component form. In the latter formulation the supersymmetry transformations are nonlinear and do not commute with all the gauge transformations. Among others, our construction yields N = 1 counterparts of recently found N = 2 supersymmetric gauge theories involving vector-tensor multiplets with gauged central charge.

Journal of High Energy Physics, 2005

We investigate membrane instanton effects in type IIA strings compactified on rigid Calabi-Yau ma... more We investigate membrane instanton effects in type IIA strings compactified on rigid Calabi-Yau manifolds. These effects contribute to the low-energy effective action of the universal hypermultiplet. In the absence of additional fivebrane instantons, the quaternionic geometry of this hypermultiplet is determined by solutions of the three-dimensional Toda equation. We construct solutions describing membrane instantons, and find perfect agreement with the string theory prediction. In the context of flux compactifications we discuss how membrane instantons contribute to the scalar potential and the stabilization of moduli. Finally, we demonstrate the existence of meta-stable de Sitter vacua.

Nuclear Physics B, 2004

We analyze the Neveu-Schwarz fivebrane instanton in type IIA string theory compactifications on r... more We analyze the Neveu-Schwarz fivebrane instanton in type IIA string theory compactifications on rigid Calabi-Yau threefolds, in the low-energy supergravity approximation. It there appears as a finite action solution to the Euclidean equations of motion of a double-tensor multiplet (dual to the universal hypermultiplet) coupled to N = 2, D = 4 supergravity. We determine the bosonic and fermionic zero modes, and the single-centered instanton measure on the moduli space of collective coordinates. The results are then used to compute, in the semiclassical approximation, correlation functions that nonperturbatively correct the universal hypermultiplet moduli space geometry of the low-energy effective action. We find that only the Ramond-Ramond sector receives corrections, and we discuss the breaking of isometries due to instantons.

Fortschritte der Physik, 2004

We expand our previous analysis on fivebrane and membrane instanton solutions in the universal hy... more We expand our previous analysis on fivebrane and membrane instanton solutions in the universal hypermultiplet, including near-extremal multi-centered solutions and mixed fivebrane-membrane charged instantons. The results are most conveniently described in terms of a double-tensor multiplet. † Talk given by S. Vandoren.

The European Physical Journal C, 1998

We describe the vector-tensor multiplet and derive its Chern-Simons coupling to the N = 2 Yang-Mi... more We describe the vector-tensor multiplet and derive its Chern-Simons coupling to the N = 2 Yang-Mills gauge superfield in harmonic superspace.

Fortschritte der Physik, 2000

We review briefly generalized Freedman-Townsend models found recently by Henneaux and Knaepen, an... more We review briefly generalized Freedman-Townsend models found recently by Henneaux and Knaepen, and provide supersymmetric versions of such models in four dimensions which couple 2-form gauge potentials and ordinary gauge fields in a gauge invariant and supersymmetric manner. The latter models have the unusual feature that, in a WZ gauge, the supersymmetry transformations do not commute with all the gauge transformations.

Classical and Quantum Gravity, 2000

We construct non-standard interactions between exterior form gauge fields by gauging a particular... more We construct non-standard interactions between exterior form gauge fields by gauging a particular global symmetry of the Einstein-Maxwell action for such fields. Furthermore we discuss generalizations of such interactions by adding couplings to gravitational Chern-Simons forms and to fields arising through dimensional reduction. The construction uses an appropriate tensor calculus.

Nuclear Physics B, 1999

We construct N = 1 supersymmetric versions of four-dimensional Freedman-Townsend models and gener... more We construct N = 1 supersymmetric versions of four-dimensional Freedman-Townsend models and generalizations thereof found recently by Henneaux and Knaepen, with couplings between 1-form and 2-form gauge potentials. The models are presented both in a superfield formulation with linearly realized supersymmetry and in WZ gauged component form. In the latter formulation the supersymmetry transformations are nonlinear and do not commute with all the gauge transformations. Among others, our construction yields N = 1 counterparts of recently found N = 2 supersymmetric gauge theories involving vector-tensor multiplets with gauged central charge.

Journal of High Energy Physics, 2005

We investigate membrane instanton effects in type IIA strings compactified on rigid Calabi-Yau ma... more We investigate membrane instanton effects in type IIA strings compactified on rigid Calabi-Yau manifolds. These effects contribute to the low-energy effective action of the universal hypermultiplet. In the absence of additional fivebrane instantons, the quaternionic geometry of this hypermultiplet is determined by solutions of the three-dimensional Toda equation. We construct solutions describing membrane instantons, and find perfect agreement with the string theory prediction. In the context of flux compactifications we discuss how membrane instantons contribute to the scalar potential and the stabilization of moduli. Finally, we demonstrate the existence of meta-stable de Sitter vacua.

Nuclear Physics B, 2004

We analyze the Neveu-Schwarz fivebrane instanton in type IIA string theory compactifications on r... more We analyze the Neveu-Schwarz fivebrane instanton in type IIA string theory compactifications on rigid Calabi-Yau threefolds, in the low-energy supergravity approximation. It there appears as a finite action solution to the Euclidean equations of motion of a double-tensor multiplet (dual to the universal hypermultiplet) coupled to N = 2, D = 4 supergravity. We determine the bosonic and fermionic zero modes, and the single-centered instanton measure on the moduli space of collective coordinates. The results are then used to compute, in the semiclassical approximation, correlation functions that nonperturbatively correct the universal hypermultiplet moduli space geometry of the low-energy effective action. We find that only the Ramond-Ramond sector receives corrections, and we discuss the breaking of isometries due to instantons.

Fortschritte der Physik, 2004

We expand our previous analysis on fivebrane and membrane instanton solutions in the universal hy... more We expand our previous analysis on fivebrane and membrane instanton solutions in the universal hypermultiplet, including near-extremal multi-centered solutions and mixed fivebrane-membrane charged instantons. The results are most conveniently described in terms of a double-tensor multiplet. † Talk given by S. Vandoren.

The European Physical Journal C, 1998

We describe the vector-tensor multiplet and derive its Chern-Simons coupling to the N = 2 Yang-Mi... more We describe the vector-tensor multiplet and derive its Chern-Simons coupling to the N = 2 Yang-Mills gauge superfield in harmonic superspace.

Fortschritte der Physik, 2000

We review briefly generalized Freedman-Townsend models found recently by Henneaux and Knaepen, an... more We review briefly generalized Freedman-Townsend models found recently by Henneaux and Knaepen, and provide supersymmetric versions of such models in four dimensions which couple 2-form gauge potentials and ordinary gauge fields in a gauge invariant and supersymmetric manner. The latter models have the unusual feature that, in a WZ gauge, the supersymmetry transformations do not commute with all the gauge transformations.