Generalized non-supersymmetric flux vacua (2008)
Lüst, Dieter, Marchesano, Fernando, Martucci, Luca, Tsimpis, Dimitrios
We discuss a novel strategy to construct 4D N=0 stable flux vacua of type II string theory, based on the existence of BPS bounds for probe D-branes in some of these backgrounds. In particular, we...
Comments on Orientifolds without Vector Structure (2008)
Bachas, Constantin, Bianchi, Massimo, Blumenhagen, Ralph, Lüst, Dieter, Weigand, Timo
We revisit type I compactifications with a Spin(32)/Z2 gauge bundle that admits no vector structure. We elucidate the relation of this Z2 obstruction to discrete B-field flux and to 't Hooft flux and...
Power of Black Hole Physics: Seeing through the Vacuum Landscape (2008)
In this paper we generalize the black hole bound of arXiv:0706.2050 to de Sitter spaces, and apply it to various vacua in the landscape, with a special emphasis on slow-roll inflationary vacua....
RTN Winter School on Strings, Supergravity and Gauge Theories (2004)
Bertolini, Matteo, Bonora, Loriano, Iengo, Roberto, Lüst, Dieter, Randjbar-Daemi, Seif
Moduli Stabilization in Chiral Type IIB Orientifold Models with Fluxes (2003)
Blumenhagen, R, Lüst, Dieter, Taylor, T R
We consider Type IIB orientifold models on Calabi-Yau spaces with three-form G-flux turned on. These fluxes freeze some of the complex structure moduli and the complex dilaton via an F-term scalar...
Intersecting 6-branes from new 7-manifolds with G(2) holonomy (2002)
Behrndt,Klaus, Dall Agata,Gianguido, Lüst,Dieter, Mahapatra,Swapna
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...
The quantum structure of spacetime and the geometric nature of fundamental interactions (2002)
Kounnas,Costas, Lüst,Dieter, Theisen,Stefan
This conference was the second annual meeting of the EU-network “The Quantum Structure of Spacetime and the Geometric Nature of Fundamental Interactions”. It took place from September 13–20,...
The quantum structure of spacetime and the geometric nature of fundamental interactions (2002)
Kounnas, Costas, Lüst, Dieter, Theisen, Stefan
This conference was the second annual meeting of the EU-network “The Quantum Structure of Spacetime and the Geometric Nature of Fundamental Interactions”. It took place from September 13–20,...
Intersecting 6-branes from new 7-manifolds with G(2) holonomy (2002)
Behrndt, Klaus, Dall Agata, Gianguido, Lüst, Dieter, Mahapatra, Swapna
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...
Curio,Gottfried, Klemm,Albrecht, Lüst,Dieter, Theisen,Stefan
We discuss the vacuum structure of type IIA/B Calabi-Yau string compactifications to four dimensions in the presence of n-form H-fluxes. These will lift the vacuum degeneracy in the Calabi-Yau moduli...
Curio, Gottfried, Klemm, Albrecht, Lüst, Dieter, Theisen, Stefan
We discuss the vacuum structure of type IIA/B Calabi-Yau string compactifications to four dimensions in the presence of n-form H-fluxes. These will lift the vacuum degeneracy in the Calabi-Yau moduli...
Continuous gauge and supersymmetry breaking for open strings on D-branes (1999)
Blumenhagen, R, Kounnas, Costas, Lüst, Dieter
We consider freely acting orbifold compactifications, which interpolate in two possible decompactification limits between the supersymmetric type II string and the non-supersymmetric type 0 string....
European Meeting on Quantum Aspects of Gauge Theories, Supersymmetry and Unification (1999)
Ceresole, Anna, Cremmer, Eugene, Derendinger, Jean-Pierre, Kounnas, Costa, Lüst, Dieter, Pioline, Boris
Aspects of type $0$ string theory (1999)
Blumenhagen, R, Font, A, Kumar, A, Lüst, Dieter
A construction of compact tachyon-free orientifolds of the non-supersymmetric Type 0B string theory is presented. Moreover, we study effective non-supersymmetric gauge theories arising on self-dual...
Space-time supersymmetry, IIA/B duality and M-theory (1999)
Abou-Zeid, Mohab, De Wit, Bernard, Lüst, Dieter, Nicolai, Hermann
The connection between IIA superstring theory compactified on a circle of radius R and IIB theory compactified on a circle of radius 1/R is reexamined from the perspective of N=2, D=9 space-time...
Workshop on Quantum Aspects of Gauge Theories, Supersymmetry and Unification (1998)
Ceresole, Anna T, Kounnas, Costas, Lüst, Dieter, Theisen, Stefan J
Higher-Order Black-Hole Solutions in N=2 Supergravity and Calabi-Yau String Backgrounds (1998)
Behrndt, Klaus, Cardoso, Gabriel Lopes, De Wit, Bernard, Lüst, Dieter, Mohaupt, Thomas, Sabra, Wafic A.
Based on special geometry, we consider corrections to N=2 extremal black-hole solutions and their entropies originating from higher-order derivative terms in N=2 supergravity. These corrections are...
From Type IIA Black Holes to T-dual Type IIB D-Instantons in N = 2, D = 4 Supergravity (1997)
In N, D Supergravity, Dieter Lüst, Klaus Behrndt, Ingo Gaida, Swapna Mahapatra, ...
We discuss the T-duality between the solutions of type IIA versus IIB superstrings compactified on Calabi-Yau threefolds. Within the context of the N = 2, D = 4 supergravity effective Lagrangian, the...
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...
On the Duality between the Heterotic String and F-Theory in 8 Dimensions (1996)
Lópes-Cardoso, G, Curio, G, Lüst, Dieter, Mohaupt, T
In this note we compare the moduli spaces of the heterotic string compactified on a two-torus and F-Theory compactified on an elliptic K3 surface for the case of an unbroken E8 x E8 gauge group. The...
Perturbative Couplings and Modular Forms in N=2 String Models with a Wilson Line (1996)
Lópes-Cardoso, G, Curio, G, Lüst, Dieter
We consider a class of four parameter D=4, N=2 string models, namely heterotic strings compactified on K3 times T2 together with their dual type II partners on Calabi-Yau three-folds. With the help...
Modular Symmetries of N=2 Black Holes (1996)
Lópes-Cardoso, G, Lüst, Dieter, Mohaupt, T
We discuss the transformation properties of classical extremal N=2 black hole solutions in S-T-U like models under S and T duality. Using invariants of (subgroups of) the triality group, which is the...
De Wit, Bernard, Lópes-Cardoso, G, Lüst, Dieter, Mohaupt, T, Rey, S J
The restrictions of target--space duality are imposed at the perturbative level on the holomorphic Wilsonian couplings that encode certain higher-order gravitational interactions in $N=2, D=4$...
De Wit, Bernard, Cardoso, Gabriel Lopes, Lüst, Dieter, Mohaupt, Thomas, Rey, Soo-Jong
The restrictions of target--space duality are imposed at the perturbative level on the holomorphic Wilsonian couplings that encode certain higher-order gravitational interactions in $N=2, D=4$...
Instanton numbers and exchange symmetries in N=2 dual string pairs (1996)
Lópes-Cardoso, G, Curio, G, Lüst, Dieter, Mohaupt, T
In this note, we comment on Calabi-Yau spaces with Hodge numbers h_{1, 1}=3 and h_{2,1}=243. We focus on the Calabi-Yau space WP_{1,1,2, 8, 12}(24) and show how some of its instanton numbers are...
Instanton Numbers and Exchange Symmetries in $N=2$ Dual String Pairs (1996)
Cardoso, Gabriel Lopes, Curio, Gottfried, Lüst, Dieter, Mohaupt, Thomas
In this note, we comment on Calabi-Yau spaces with Hodge numbers $h_{1,1}=3$ and $h_{2,1}=243$. We focus on the Calabi-Yau space $WP_{1,1,2,8,12}(24)$ and show how some of its instanton numbers are...
Perturbative and non-perturbative monodromies in N=2 heterotic string vacua (1996)
Cardoso, Gabriel Lopes, Lüst, Dieter, Mohaupt, Thomas
In this talk we summarise our recent results on perturbative and non-perturbative monodromies in four-dimensional heterotic strings with $N=2$ space-time supersymmetry, and we compare our results...
Modular Symmetries Of N=2 Black Holes (1996)
N Black Holes, Dieter Lüst, Gabriel Lopes Cardoso, Thomas Mohaupt
We discuss the transformation properties of classical extremal N = 2 black hole solutions in S-T -U like models under S and T duality. Using invariants of (subgroups of) the triality group, which is...
Perturbative and non-perturbative monodromies in N=2 heterotic string vacua (1996)
Gabriel Lopes Cardoso, Dieter Lüst, Thomas Mohaupt, Weyl Reflections
this paper, only consider the T = U 6= 1; ae
On The Duality Between The Heterotic String And F-Theory In 8 Dimensions (1996)
Gabriel Lopes Cardoso, Gottfried Curio, Dieter Lüst, Thomas Mohaupt
In this note we compare the moduli spaces of the heterotic string compactified on a two--torus and F--Theory compactified on an elliptic K3 surface for the case of an unbroken E 8 \Theta E 8 gauge...
Classical And Quantum N = 2 Supersymmetric Black Holes (1996)
Black Holes, Klaus Behrndt, Gabriel Lopes Cardoso, Bernard De Wit, Dieter Lüst, Renata Kallosh, ...
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...
Instanton Numbers and Exchange Symmetries in N=2 Dual String Pairs (1996)
Gabriel Lopes Cardoso, Gottfried Curio, Dieter Lüst, Thomas Mohaupt
In this note, we comment on Calabi-Yau spaces with Hodge numbers h 1;1 = 3 and h 2;1 = 243. We focus on the Calabi-Yau space WP 1;1;2;8;12 (24) and show how some of its instanton numbers are related...
Lópes-Cardoso, G, Curio, G, Lüst, Dieter, Mohaupt, T, Rey, S J
We study the BPS spectrum in D=4, N=4 heterotic string compactifications, with some emphasis on intermediate N=4 BPS states. These intermediate states, which can become short in N=2...
Perturbative and non-perturbative results for N=2 heterotic strings (1995)
Lópes-Cardoso, G, Mohaupt, T, Lüst, Dieter
In this paper we summarize our recent work about perturbative and non-perturbative effects in four-dimensional heterotic strings with N=2 space-time supersymmetry.
Perturbative and non-perturbative results for N=2 heterotic strings (1995)
Lópes-Cardoso, G, Lüst, Dieter, Mohaupt, T
In this paper we summarize our recent work about perturbative and non-perturbative effects in four-dimensional heterotic strings with N=2 space-time supersymmetry.
Non-perturbative monodromies in N=2 heterotic string vacua (1995)
Cardoso, Gabriel Lopes, Lüst, Dieter, Mohaupt, Thomas
We address non-perturbative effects and duality symmetries in $N=2$ heterotic string theories in four dimensions. Specifically, we consider how each of the four lines of enhanced gauge symmetries in...
Perturbative and Non-Perturbative Results for N=2 Heterotic Strings (1995)
Gabriel Lopes Cardoso, Dieter Lüst, Thomas Mohaupt
this paper we summarize our recent work about perturbative and non-perturbative effects in four-dimensional heterotic strings with N = 2 space-time supersymmetry. 1. Introduction
Gabriel Lopes Cardoso, Gottfried Curio, Dieter Lüst, Thomas Mohaupt, Soo-jong Rey
We study the BPS spectrum in D = 4; N = 4 heterotic string compactifications, with some emphasis on intermediate N = 4 BPS states. These intermediate states, which can become short in N = 2...
Threshold Corrections and Symmetry Enhancement in String Compactifications (1994)
Cardoso, Gabriel Lopes, Lüst, Dieter, Mohaupt, Thomas
We present the computation of threshold functions for Abelian orbifold compactifications. Specifically, starting from the massive, moduli-dependent string spectrum after compactification, we derive...
Cardoso, Gabriel Lopes, Lüst, Dieter
In this letter we discuss the relation of four-dimensional, $N=2$ supersymmetric string backgrounds to integrable models. In particular we show that non-K\"ahlerian gravitational backgrounds with one...
Cardoso, Gabriel Lopes, Lüst, Dieter, Ovrut, Burt A.
It is pointed out that massive states in D=4, N=1 supergravity-matter theories can, in general, at the 1-loop level contribute non-holomorphic terms to quadratic gravitational couplings. It is then...
Superstring gravitational wave backgrounds with spacetime supersymmetry (1994)
Kiritsis, Elias B, Kounnas, Costas, Lüst, Dieter
We analyse the stringy gravitational wave background based on the current algebra E.sup(c).sub(2). We determine its exact spectrum and construct the modular invariant vacuum energy. The corresponding...
Threshold Corrections And Symmetry Enhancement In String Compactifications (1994)
Gabriel Lopes Cardoso, Dieter Lüst, Thomas Mohaupt
We present the computation of threshold functions for Abelian orbifold compactifications. Specifically, starting from the massive, moduli-dependent string spectrum after compactification, we derive...
Gabriel Lopes Cardoso, Dieter Lüst, Thomas Monhaupt
We present the coset structure of the untwisted moduli space of heterotic (0; 2) ZN orbifold compactifications with continuous Wilson lines. For the cases where the internal 6-torus T 6 is given by...
Some Results On (0,2) Z_N Orbifold Theories WITH CONTINUOUS WILSON LINES (1994)
Gabriel Lopes Cardoso, DIETER Lüst, Dieter L, Thomas Mohaupt
We discuss recent results on orbifold compactifications with (0,2) world sheet supersymmetry and continuous Wilson lines, emphasizing the role of modular symmetries. 1. Introduction Orbifold...
Duality Symmetries and Supersymmetry Breaking in String Compactifications (1994)
Gabriel Lopes Cardoso, Dieter Lüst, Thomas Monhaupt
We discuss the spontaneous supersymetry breaking within the low-energy effective supergravity action of four-dimensional superstrings. In particular, we emphasize the non-universality of the soft...
Non-compact Calabi-Yau spaces and other non-trivial backgrounds for 4-d superstrings (1993)
Kiritsis, Elias B, Lüst, Dieter, Kounnas, Costas
A large class of new 4-D superstring vacua with non-trivial/singular geometries, spacetime supersymmetry and other background fields (axion, dilaton) are found. Killing symmetries are generic and are...
Non-compact Calabi-Yau spaces and other non-trivial backgrounds for 4-d superstrings (1993)
Kiritsis, Elias B, Kounnas, Costas, Lüst, Dieter
A large class of new 4-D superstring vacua with non-trivial/singular geometries, spacetime supersymmetry and other background fields (axion, dilaton) are found. Killing symmetries are generic and are...
A large class of new gravitational and axionic backgrounds for four-dimensional superstrings (1993)
Kiritsis, Elias B, Kounnas, Costas, Lüst, Dieter
A large class of new 4-D superstring vacua with non-trivial/singular geometries, spacetime supersymmetry and other background fields (axion, dilaton) are found. Killing symmetries are generic and are...
Cosmological string backgrounds (1993)
Talk given at the ``4th Hellenic School on Elementary Particle Physics", Corfu, 2-20 September 1992: The propagation of strings in cosmological space-time backgrounds is reviewed. We show the...
Consistency and phenomenology of four-dimensional strings (1993)
Talk given at the 26th Workshop: ``From Superstrings to Supergravity" Erice - Sicily, 5-12 December 1992: In this talk we discuss string consistency requirements on four dimensional string models,...
Cosmological string backgrounds from gauged WZW models (1992)
We discuss the four-dimensional target-space interpretation of bosonic strings based on gauged WZW models, in particular of those based on the non-compact coset space $SL(2,{\bf R})\times SO(1,1)^2...
We present a systematic study of the constraints coming from target-space duality and the associated duality anomaly cancellations on orbifold-like 4-D strings. A prominent role is played by the...
The duality-invariant gaugino condensation with or without massive matter fields is re-analysed, taking into account the dependence of the string threshold corrections on the moduli fields and recent...
Automorphic functions and special Kähler geometry (1991)
Ferrara, Sergio, Kounnas, Costas, Lüst, Dieter, Zwirner, Fabio
The top quark mass in t-$\overline{t}$ condensation models with enlarged bound-state spectrum (1991)
Target space duality, supersymmetry breaking and the stability of classical string vacua (1991)
Cvetic, M, Font, A, Ibáñez, L E, Lüst, Dieter, Quevedo, Fernando
Some considerations about the stringy Higgs effect (1991)
Ibanez, L., Lerche, Wolfgang, Lüst, Dieter, Theisen, Stefan
We discuss various aspects of the Higgs mechanism that takes place in string theories, by considering the Z3 heterotic orbifold as a specific example. Some emphasis is put on the duality invariance...
Some considerations about the stringy Higgs effect (1990)
Ibáñez, L E, Lerche, Wolfgang, Lüst, Dieter, Theisen, Stefan J
Phenomenology of high colour fermions (1990)
Lüst, Dieter, Papantonopoulos, E, Streng, K H, Zoupanos, George
Modular invariance in supersymmetric field theories (1990)
Ferrara, Sergio, Lüst, Dieter, Shapere, A D, Theisen, Stefan J
Duality transformations for blown-up orbifolds (1990)
Ferrara, Sergio, Lüst, Dieter, Theisen, Stefan
Assuming that the duality symmetry present for heterotic orbifold compactifications extends to the blow-up orbifold, we derive conditions for the Kähler potential for the moduli and for the cubic...
World-sheet versus spectrum symmetries in heterotic and type II superstrings (1990)
Ferrara, Sergio, Lüst, Dieter, Theisen, Stefan
We discuss the relation between world-sheet symmetries of general four-dimensional superstring theories and the classification of their massless and massive excitations. This follows from the...
Modular invariance in supersymmetric field theories (1989)
Ferrara, Sergio, Lüst, Dieter, Shapere, A., Theisen, Stefan
We show how duality invariance of the supergravity action restricts the Kähler potential and the superpotential and connects them to the theory of modular forms. This has relevance in string-induced...
Target space modular invariance and low-energy couplings in orbifold compacifications (1989)
Ferrara, Sergio, Lüst, Dieter, Theisen, Stefan
We show how the action of the target space modular group restricts the parameters of the low-energy effective action of orbifold compactifications. These constraints are shown to be consistent with...
Exceptional groups in string theory (1989)
We review the occurrence of exceptional groups in string theory: their dual role as gauge symmetry and as a symmetry unifying space-time, superconformal ghost and internal degrees of freedom. In both...
Superstring partition functions and the characters of exceptional groups (1989)
We study the relation between the one-loop partition function of supersymmetric four-dimensional heterotic string theories and the level-one characters of exceptional groups. This is used to derive...
Lectures on string theory (1989)
The book presents an extended version of the lectures on string theory which were given by the authors in 1987-1988 at the Max-Planck Institut für Physik und Astrophysik in Munich. It can be...
Factorization properties of genus-two bosonic and fermionic string partition functions (1988)
Koh, In-Gyu, Lüst, Dieter, Theisen, Stefan
The genus-two bosonic and fermionic string partition functions factorize, in the separating pinching limit, into genus-one partition functions after integrating out the supermoduli with...
Four-dimensional supergravity from four-dimensional strings (1988)
Lauer, Jürgen, Lüst, Dieter, Theisen, Stefan
We consider four-dimensional N = 1 supersymmetric heterotic string theories. It is shown how an underlying E6 symmetry organizes the (massless) states into supermultiplets. Scattering amplitudes in...
Supersymmetric string theories, superconformal algebras and exceptional groups (1988)
Lauer, Jürgen, Lüst, Dieter, Theisen, Stefan
We study the relation between extended space-time supersymmetry and extended worldsheet symmetries within the context of four-dimensional heterotic string theories. It is shown how these symmetries...
Four-dimensional heterotic strings-orbifolds and covariant lattices (1988)
Two - so far unrelated - constructions of four-dimensional heterotic string theories are discussed within a common framework. We show that four-dimensional heterotic string theories which are based...
Four-dimensional heterotic strings and conformal field theory (1988)
Lüst, Dieter, Theisen, Stefan, Zoupanos, George
The techniques of (super) conformal field theory are applied to 4-dimensional heterotic string theories. We discuss certain aspects of 4-dimensional strings in the framework of the bosonic lattice...
Four-Dimensional Heterotic Strings and Their Field Theory Limits (1988)
Lüst, Dieter, Theisen, Stefan, Zoupanos, George
The construction of heterotic string theories in d less then 10 dimensions is reviewed within the framework of the covariant lattice approach. Methods of (super) conformal field theory, necessary to...