Intersecting 6-branes from new 7-manifolds with G_2 holonomy (2002)
Behrndt, K., Dall'Agata, G., Lüst, D., Mahapatra, S.
We discuss a new family of metrics of 7-manifolds with G_2 holonomy, which are R^3 bundles over a quaternionic space. The metrics depend on five parameters and have two Abelian isometries. Certain...
Massive dualities in six dimensions (2002)
Sundell, P., Roest, D., Bergshoeff, E., Behrndt, K.
We study compactifications of string theory and M-theory to six dimensions with background fluxes. The non-zero fluxes lead to additional mass parameters. We derive the S- and T-duality rules for the...
Massive Dualities in Six Dimensions (2001)
Behrndt, K., Bergshoeff, E., Roest, D., Sundell, P.
We study compactifications of string theory and M-theory to six dimensions with background fluxes. The nonzero fluxes lead to additional mass parameters. We derive the S- and T-duality rules for the...
Non-Extreme Black Holes of Five Dimensional N=2 AdS Supergravity (1998)
Behrndt, K., Cvetic, M., Sabra, W. A.
We derive and analyse the full set of equations of motion for non-extreme static black holes (including examples with the spatial curvatures k=-1 and k=0) in D=5 N=2 gauged supergravity by employing...
BPS black holes in N=2 five dimensional AdS supergravity (1998)
Behrndt, K., Chamseddine, A. H., Sabra, W. A.
BPS black hole solutions of U(1) gauged five-dimensional supergravity are obtained by solving the Killing spinor equations. These extremal static black holes live in an asymptotic AdS_5 space time....
D-Instantons and asymptotic geometries (1998)
The large N limit of D3-branes is expected to correspond to a superconformal field theory living on the boundary of the anti-de Sitter space appearing in the near-horizon geometry. Dualizing the...
D-instantons and asymptotic geometries (1998)
The large-N limit of D-3-branes is expected to correspond to a superconformal field theory living on the boundary of the anti-de Sitter space appearing in the near-horizon geometry. Dualizing the...
Quantum N = 2 Supersymmetric Black Holes in the S-T Model (1997)
Behrndt, K, Lópes-Cardoso, G, Gaida, I
We consider axion-free quantum corrected black hole solutions in the context of the heterotic S-T model with half the N=2, D=4 supersymmetries unbroken. We express the perturbatively corrected...
Quantum N = 2 Supersymmetric Black Holes in the S-T Model (1997)
Behrndt, K., Cardoso, G. Lopes, Gaida, I.
We consider axion-free quantum corrected black hole solutions in the context of the heterotic S-T model with half the N=2, D=4 supersymmetries unbroken. We express the perturbatively corrected...
Static N=2 Black Holes For Quadratic Prepotentials (1997)
We employ the principle of minimal central charge and study the entropy of N=2 black holes corresponding to the most general quadratic prepotential. We also give a static black hole solution for...
D-instantons and black holes in N=2, D=4 supergravity (1997)
K. Behrndt, I. Gaida, D. Lüst, S. Mahapatra, T. Mohaupt
: We discuss T-duality between the solutions of type II A versus type II B superstrings compactified on Calabi-Yau threefolds. Within the context of N = 2, D = 4 supergravity effective Lagrangian,...
Classical and quantum N=2 supersymmetric black holes (1996)
Behrndt, K, Lópes-Cardoso, G, De Wit, Bernard, Kallosh, Renata E, Lüst, Dieter, Mohaupt, T
We use heterotic/type-II prepotentials to study quantum/classical black holes with half the $N=2, D=4$ supersymmetries unbroken. We show that, in the case of heterotic string compactifications, the...
Classical and quantum N=2 supersymmetric black holes (1996)
Behrndt, K., Cardoso, G. Lopes, De Wit, B., Kallosh, R., Lüst, D., Mohaupt, T.
We use heterotic/type-II prepotentials to study quantum/classical black holes with half the $N=2, D=4$ supersymmetries unbroken. We show that, in the case of heterotic string compactifications, the...
A Note on Intersecting $D$-branes and Black Hole Entropy (1996)
In four dimensions there are 4 different types of extremal Maxwell/scalar black holes characterized by a scalar coupling parameter $a$ with $a=0,1/\sqrt{3} , 1 , \sqrt{3}$. These black holes can be...
Type II Duality Symmetries in Six Dimensions (1995)
Behrndt, K., Bergshoeff, E., Janssen, Bert
We discuss the different discrete duality symmetries in six dimensions that act within and between (i) the 10-dimensional heterotic string compactified on $T^4$, (ii) the 10-dimensional Type IIA...
String-string duality for some black hole type solutions (1995)
We apply the duality transformation relating the heterotic to the IIA string in 6D to the class of exact string solutions described by the chiral null model and derive explicit formulas for all...
String duality and massless string states (1995)
We are discussing the $S$ \& $T$ duality for special class of heterotic string configurations. This class of solutions includes various types of black hole solutions and Taub-NUT geometries. It...
About a class of exact string backgrounds (1995)
This model also known as chiral null model is a generalization of the gravitational wave and fundamental string background and is exact in the $\a'$ expansion. The reduction to 4 dimensions yields a...
Creation of a scalar potential in 2D dilaton gravity (1994)
We investigate quantum corrections of the 2-d dilaton gravity near the singularity. Our motivation comes from a s-wave reduced cosmological solution which is classically singular in the scalar fields...
Quantum Corrections for a Cosmological String Solution (1994)
We investigate quantum corrections for a cosmological solution of the string effective action. Starting point is a classical solution containing an antisymmetric tensor field, a dilaton and a modulus...
Towards Quantum Cosmology without Singularities (1994)
In this paper we investigate the vanishing of cosmological singularities by quantization. Starting from a 5d Kaluza--Klein approach we quantize, as a first step, the non--spherical metric part and...
String--Kaluza--Klein Cosmology (1994)
We generalize a five dimensional black hole solution of low energy effective string theory to arbitrary constant spatial curvature. After interchanging the signature of time and radius we reduce the...
Cosmological String Solutions by Dimensional Reduction (1993)
We obtain cosmological four dimensional solutions of the low energy effective string theory by reducing a five dimensional black hole, and black hole--de Sitter solution of the Einstein gravity down...
Cosmological String Solutions in 4 Dimensions from 5d Black Holes (1993)
We obtain cosmological four dimensional solutions of the low energy effective string theory by reducing a five dimensional black hole, and black hole--de Sitter solution of Einstein gravity down to...
A Monopole Solution in open String Theory (1993)
We investigate a solution of the Weyl invariance conditions in open string theory in 4 dimensions. In the closed string sector this solution is a combination of the SU(2) Wess--Zumino--Witten model...
The Tachyon in a Linear Expanding Universe (1992)
We investigate the tachyon coupling in a static Robertson--Walker like metric background. For a tachyon and dilaton field which are only time dependent one can rewrite this model as a SU(2)...
Non-Critical Strings in Robertson-Walker Space Time (1992)
I consider a D+1 dimensional nonlinear $\sigma$ model based on a possible interpretation of the Liouville field as a physical time. The Weyl invariance of this theory gives us restrictions for the...