Two Higgs Pair Heterotic Vacua and Flavor-Changing Neutral Currents (2008)
Ambroso, Michael, Braun, Volker, Ovrut, Burt A.
We present a vacuum of heterotic M-theory whose observable sector has the MSSM spectrum with the addition of one extra pair of Higgs-Higgs conjugate superfields. The quarks/leptons have a realistic...
Eigenvalues and Eigenfunctions of the Scalar Laplace Operator on Calabi-Yau Manifolds (2008)
Braun, Volker, Brelidze, Tamaz, Douglas, Michael R., Ovrut, Burt A.
A numerical algorithm for explicitly computing the spectrum of the Laplace-Beltrami operator on Calabi-Yau threefolds is presented. The requisite Ricci-flat metrics are calculated using a method...
Worldsheet Instantons and Torsion Curves (2008)
Braun, Volker, Kreuzer, Maximilian, Ovrut, Burt A., Scheidegger, Emanuel
We study aspects of worldsheet instantons relevant to a heterotic standard model. The non-simply connected Calabi-Yau threefold used admits Z_3 x Z_3 Wilson lines, and a more detailed investigation...
Calabi-Yau Metrics for Quotients and Complete Intersections (2007)
Braun, Volker, Brelidze, Tamaz, Douglas, Michael R., Ovrut, Burt A.
We extend previous computations of Calabi-Yau metrics on projective hypersurfaces to free quotients, complete intersections, and free quotients of complete intersections. In particular, we construct...
Higher Derivative Gravitation in Superstrings (2007)
It is shown that non-vanishing (C mnpq ) 2 terms arise in N=1, D=4 superstring Lagrangians due to one-loop radiative corrections with light field internal lines. (2,2) Symmetric ZN Orbifolds Although...
Non-Gaussianities in New Ekpyrotic Cosmology (2007)
Buchbinder, Evgeny I., Khoury, Justin, Ovrut, Burt A.
New Ekpyrotic Cosmology is an alternative scenario of the early universe which relies on a phase of slow contraction before the big bang. We calculate the 3-point and 4-point correlation functions of...
On the Initial Conditions in New Ekpyrotic Cosmology (2007)
Buchbinder, Evgeny I., Khoury, Justin, Ovrut, Burt A.
New Ekpyrotic Cosmology is an alternative scenario of early universe cosmology in which the universe existed before the big bang. The simplest model relies on two scalar fields, whose entropy...
Worldsheet Instantons and Torsion Curves, Part B: Mirror Symmetry (2007)
Braun, Volker, Kreuzer, Maximilian, Ovrut, Burt A., Scheidegger, Emanuel
We apply mirror symmetry to the problem of counting holomorphic rational curves in a Calabi-Yau threefold X with Z_3 x Z_3 Wilson lines. As we found in Part A [hep-th/0703182], the integral homology...
Worldsheet Instantons and Torsion Curves, Part A: Direct Computation (2007)
Braun, Volker, Kreuzer, Maximilian, Ovrut, Burt A., Scheidegger, Emanuel
As a first step towards studying vector bundle moduli in realistic heterotic compactifications, we identify all holomorphic rational curves in a Calabi-Yau threefold X with Z_3 x Z_3 Wilson lines....
Worldsheet Instantons, Torsion Curves, and Non-Perturbative Superpotentials (2007)
Braun, Volker, Kreuzer, Maximilian, Ovrut, Burt A., Scheidegger, Emanuel
As a first step towards computing instanton-generated superpotentials in heterotic standard model vacua, we determine the Gromov-Witten invariants for a Calabi-Yau threefold with fundamental group...
New Ekpyrotic Cosmology (2007)
Buchbinder, Evgeny I., Khoury, Justin, Ovrut, Burt A.
In this paper, we present a new scenario of the early Universe that contains a pre big bang Ekpyrotic phase. By combining this with a ghost condensate, the theory explicitly violates the null energy...
Towards Realizing Dynamical SUSY Breaking in Heterotic Model Building (2006)
Braun, Volker, Buchbinder, Evgeny I., Ovrut, Burt A.
We study a new mechanism to dynamically break supersymmetry in the E8xE8 heterotic string. As discussed recently in the literature, a long-lived, meta-stable non-supersymmetric vacuum can be achieved...
Dynamical SUSY Breaking in Heterotic M-Theory (2006)
Braun, Volker, Buchbinder, Evgeny I., Ovrut, Burt A.
It is shown that four-dimensional N=1 supersymmetric QCD with massive flavors in the fundamental representation of the gauge group can be realized in the hidden sector of E8xE8 heterotic string...
Stabilizing Moduli with a Positive Cosmological Constant in Heterotic M-Theory (2006)
It is shown that strongly coupled heterotic M-theory with anti-five-branes in the S^1/Z_2 bulk space can have meta-stable vacua which break N=1 supersymmetry and have a small, positive cosmological...
Stability of the Minimal Heterotic Standard Model Bundle (2006)
Braun, Volker, He, Yang-Hui, Ovrut, Burt A.
The observable sector of the "minimal heterotic standard model" has precisely the matter spectrum of the MSSM: three families of quarks and leptons, each with a right-handed neutrino, and one...
Yukawa Couplings in Heterotic Standard Models (2006)
Braun, Volker, He, Yang-Hui, Ovrut, Burt A.
In this paper, we present a formalism for computing the Yukawa couplings in heterotic standard models. This is accomplished by calculating the relevant triple products of cohomology groups, leading...
The Exact MSSM Spectrum from String Theory (2005)
Braun, Volker, He, Yang-Hui, Ovrut, Burt A., Pantev, Tony
We show the existence of realistic vacua in string theory whose observable sector has exactly the matter content of the MSSM. This is achieved by compactifying the E_8 x E_8 heterotic superstring on...
Moduli Dependent mu-Terms in a Heterotic Standard Model (2005)
Braun, Volker, He, Yang-Hui, Ovrut, Burt A., Pantev, Tony
In this paper, we present a formalism for computing the non-vanishing Higgs mu-terms in a heterotic standard model. This is accomplished by calculating the cubic product of the cohomology groups...
Heterotic Standard Model Moduli (2005)
Braun, Volker, He, Yang-Hui, Ovrut, Burt A., Pantev, Tony
In previous papers, we introduced a heterotic standard model and discussed its basic properties. The Calabi-Yau threefold has, generically, three Kahler and three complex structure moduli. The...
The Dynamics of Small Instanton Phase Transitions (2005)
Borisov, Alexander, Buchbinder, Evgeny I., Ovrut, Burt A.
The small instanton transition of a five-brane colliding with one end of the S1/Z2 interval in heterotic M-theory is discussed, with emphasis on the transition moduli, their potential function and...
Vector Bundle Extensions, Sheaf Cohomology, and the Heterotic Standard Model (2005)
Braun, Volker, He, Yang-Hui, Ovrut, Burt A., Pantev, Tony
Stable, holomorphic vector bundles are constructed on an torus fibered, non-simply connected Calabi-Yau threefold using the method of bundle extensions. Since the manifold is multiply connected, we...
A Standard Model from the E8 x E8 Heterotic Superstring (2005)
Braun, Volker, He, Yang-Hui, Ovrut, Burt A., Pantev, Tony
In a previous paper, we introduced a heterotic standard model and discussed its basic properties. This vacuum has the spectrum of the MSSM with one additional pair of Higgs-Higgs conjugate fields and...
A Heterotic Standard Model (2005)
Braun, Volker, He, Yang-Hui, Ovrut, Burt A., Pantev, Tony
Within the context of the E_8 x E_8 heterotic superstring compactified on a smooth Calabi-Yau threefold with an SU(4) gauge instanton, we show the existence of simple, realistic N=1 supersymmetric...
The Spectra of Heterotic Standard Model Vacua (2004)
Donagi, Ron, He, Yang-Hui, Ovrut, Burt A., Reinbacher, Rene
A formalism for determining the massless spectrum of a class of realistic heterotic string vacua is presented. These vacua, which consist of SU(5) holomorphic bundles on torus-fibered Calabi-Yau...
Instanton Moduli in String Theory (2004)
Buchbinder, Evgeny I., Ovrut, Burt A., Reinbacher, Rene
Expressions for the number of moduli of arbitrary SU(n) vector bundles constructed via Fourier-Mukai transforms of spectral data over Calabi- Yau threefolds are derived and presented. This is done...
Elliptic Calabi-Yau Threefolds with Z_3 x Z_3 Wilson Lines (2004)
Braun, Volker, Ovrut, Burt A., Pantev, Tony, Reinbacher, Rene
A torus fibered Calabi-Yau threefold with first homotopy group Z_3 x Z_3 is constructed as a free quotient of a fiber product of two dP_9 surfaces. Calabi-Yau threefolds of this type admit Z_3 x Z_3...
The Particle Spectrum of Heterotic Compactifications (2004)
Donagi, Ron, He, Yang-Hui, Ovrut, Burt A., Reinbacher, Rene
Techniques are presented for computing the cohomology of stable, holomorphic vector bundles over elliptically fibered Calabi-Yau threefolds. These cohomology groups explicitly determine the spectrum...
Moduli Dependent Spectra of Heterotic Compactifications (2004)
Donagi, Ron, He, Yang-Hui, Ovrut, Burt A., Reinbacher, Rene
Explicit methods are presented for computing the cohomology of stable, holomorphic vector bundles on elliptically fibered Calabi-Yau threefolds. The complete particle spectrum of the low-energy,...
Vacuum Stability in Heterotic M-Theory (2003)
Buchbinder, Evgeny I., Ovrut, Burt A.
The problem of the stabilization of moduli is discussed within the context of compactified strongly coupled heterotic string theory. It is shown that all geometric, vector bundle and five-brane...
Global Fluctuation Spectra in Big Crunch/Big Bang String Vacua (2003)
We study Big Crunch/Big Bang cosmologies that correspond to exact world-sheet superconformal field theories of type II strings. The string theory spacetime contains a Big Crunch and a Big Bang...
SU(4) Instantons on Calabi-Yau Threefolds with Z_2 x Z_2 Fundamental Group (2003)
Donagi, Ron, Ovrut, Burt A., Pantev, Tony, Reinbacher, Rene
Structure group SU(4) gauge vacua of both weakly and strongly coupled heterotic superstring theory compactified on torus-fibered Calabi-Yau threefolds Z with Z_2 x Z_2 fundamental group are...
The Moduli of Reducible Vector Bundles (2003)
He, Yang-Hui, Ovrut, Burt A., Reinbacher, Rene
A procedure for computing the dimensions of the moduli spaces of reducible, holomorphic vector bundles on elliptically fibered Calabi-Yau threefolds X is presented. This procedure is applied to...
Invariant Homology on Standard Model Manifolds (2003)
Ovrut, Burt A., Pantev, Tony, Reinbacher, Rene
Torus-fibered Calabi-Yau threefolds Z, with base dP_9 and fundamental group pi_1(Z)=Z_2 X Z_2, are reviewed. It is shown that Z=X/(Z_2 X Z_2), where X=B X_{P_1} B' are elliptically fibered Calabi-Yau...
Torus-Fibered Calabi-Yau Threefolds with Non-Trivial Fundamental Group (2002)
Ovrut, Burt A., Pantev, Tony, Reinbacher, Rene
We construct smooth Calabi-Yau threefolds Z, torus-fibered over a dP_9 base, with fundamental group Z_2 X Z_2. To do this, the structure of rational elliptic surfaces is studied and it is shown that...
Vector Bundle Moduli Superpotentials in Heterotic Superstrings and M-Theory (2002)
Buchbinder, Evgeny I., Donagi, Ron, Ovrut, Burt A.
The non-perturbative superpotential generated by a heterotic superstring wrapped once around a genus-zero holomorphic curve is proportional to the Pfaffian involving the determinant of a Dirac...
Superpotentials for Vector Bundle Moduli (2002)
Buchbinder, Evgeny I., Donagi, Ron, Ovrut, Burt A.
We present a method for explicitly computing the non-perturbative superpotentials associated with the vector bundle moduli in heterotic superstrings and M-theory. This method is applicable to any...
Vector Bundle Moduli and Small Instanton Transitions (2002)
Buchbinder, Evgeny, Donagi, Ron, Ovrut, Burt A.
We give the general presciption for calculating the moduli of irreducible, stable SU(n) holomorphic vector bundles with positive spectral covers over elliptically fibered Calabi-Yau threefolds....
Lectures on Heterotic M-Theory (2002)
We present three lectures on heterotic M-theory and a fourth lecture extending this theory to more general orbifolds. In Lecture 1, Horava-Witten theory is briefly discussed. We then compactify this...
Knots, Braids and BPS States in M-Theory (2001)
Grassi, Antonella, Guralnik, Zachary, Ovrut, Burt A.
In previous work we considered M-theory five branes wrapped on elliptic Calabi-Yau threefold near the smooth part of the discriminant curve. In this paper, we extend that work to compute the light...
Density Perturbations in the Ekpyrotic Scenario (2001)
Khoury, Justin, Ovrut, Burt A., Steinhardt, Paul J., Turok, Neil
We study the generation of density perturbations in the ekpyrotic scenario for the early universe, including gravitational backreaction. We expose interesting subtleties that apply to both...
From Big Crunch to Big Bang (2001)
Khoury, Justin, Ovrut, Burt A., Seiberg, Nathan, Steinhardt, Paul J., Turok, Neil
We consider conditions under which a universe contracting towards a big crunch can make a transition to an expanding big bang universe. A promising example is 11-dimensional M-theory in which the...
Four-Dimensional N=1 Super Yang-Mills Theory from an M-Theory Orbifold (2001)
Doran, Charles F., Faux, Michael, Ovrut, Burt A.
Gravitational and gauge anomalies provide stringent constraints on which subset of chiral models can effectively describe M-theory at low energy. In this paper, we explicitly construct an abelian...
A Brief Comment on "The Pyrotechnic Universe" (2001)
Khoury, Justin, Ovrut, Burt A., Steinhardt, Paul J., Turok, Neil
We respond to the criticisms by Kallosh, Kofman and Linde concerning our proposal of the ekpyrotic universe scenario. We point out a number of errors in their considerations and argue that, at this...
Visible Branes with Negative Tension in Heterotic M-Theory (2001)
Donagi, Ron Y., Khoury, Justin, Ovrut, Burt A., Steinhardt, Paul J., Turok, Neil
It is shown that there exist large classes of BPS vacua in heterotic M-theory which have negative tension on the visible orbifold plane, positive tension on the hidden plane and positive tension,...
The Ekpyrotic Universe: Colliding Branes and the Origin of the Hot Big Bang (2001)
Khoury, Justin, Ovrut, Burt A., Steinhardt, Paul J., Turok, Neil
We propose a cosmological scenario in which the hot big bang universe is produced by the collision of a brane in the bulk space with a bounding orbifold plane, beginning from an otherwise cold,...
Local Anomaly Cancellation, M-Theory Orbifolds and Phase-Transitions (2000)
Faux, Michael, Lust, Dieter, Ovrut, Burt A.
In this paper we consider orbifold compactifications of M-theory on $S^1/{\bf Z}_2\times T^4/{\bf Z}_2$. We discuss solutions of the local anomaly matching conditions by twisted vector, tensor and...
Heterotic M-Theory Cosmology in Four and Five Dimensions (2000)
Braendle, Matthias, Lukas, Andre, Ovrut, Burt A.
We study rolling radii solutions in the context of the four- and five-dimensional effective actions of heterotic M-theory. For the standard four-dimensional solutions with varying dilaton and...
Small Instanton Transitions in Heterotic M-Theory (2000)
Ovrut, Burt A., Pantev, Tony, Park, Jaemo
We discuss non-perturbative phase transitions, within the context of heterotic M-theory, which occur when all, or part, of the wrapped five-branes in the five-dimensional bulk space come into direct...
A Cosmological Mechanism for Stabilizing Moduli (2000)
Huey, Greg, Steinhardt, Paul J., Ovrut, Burt A., Waldram, Daniel
In this paper, we show how the generic coupling of moduli to the kinetic energy of ordinary matter fields results in a cosmological mechanism that influences the evolution and stability of moduli. As...
Standard Model Vacua in Heterotic M-Theory (2000)
Donagi, Ron, Ovrut, Burt A., Pantev, Tony, Waldram, Daniel
We present a class of N=1 supersymmetric ``standard'' models of particle physics, derived directly from heterotic M-theory, that contain three families of chiral quarks and leptons coupled to the...
Standard Models from Heterotic M-theory (1999)
Donagi, Ron, Ovrut, Burt A., Pantev, Tony, Waldram, Daniel
We present a class of N=1 supersymmetric models of particle physics, derived directly from heterotic M-theory, that contain three families of chiral quarks and leptons coupled to the gauge group...
Symmetric Vacua in Heterotic M-Theory (1999)
Symmetric vacua of heterotic M-theory, characterized by vanishing cohomology classes of individual sources in the three-form Bianchi identity, are analyzed on smooth Calabi-Yau three-folds. We show...
N=1 Supersymmetric Vacua in Heterotic M-Theory (1999)
In the first lecture, we derive the five-dimensional effective action of strongly coupled heterotic string theory for the complete (1,1) sector of the theory by performing a reduction, on a...
Moduli Spaces of Fivebranes on Elliptic Calabi-Yau Threefolds (1999)
Donagi, Ron, Ovrut, Burt A., Waldram, Daniel
We present a general method for calculating the moduli spaces of fivebranes wrapped on holomorphic curves in elliptically fibered Calabi-Yau threefolds, in particular, in the context of heterotic M...
Heterotic M-Theory Vacua with Five-Branes (1999)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
We construct vacua of heterotic M-theory with general gauge bundles and five-branes. Some aspects of the resulting low-energy effective theories are discussed.
Intersecting Orbifold Planes and Local Anomaly Cancellation in M-Theory (1999)
Faux, Michael, Luest, Dieter, Ovrut, Burt A.
A systematic program is developed for analyzing and cancelling local anomalies on networks of intersecting orbifold planes in the context of M-theory. Through a delicate balance of factors, it is...
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
Inflationary solutions are constructed in a specific five-dimensional model with boundaries motivated by heterotic M-theory. We concentrate on the case where the vacuum energy is provided by...
Five--Branes and Supersymmetry Breaking in M--Theory (1999)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
Supersymmetry breaking via gaugino condensation is studied in vacua of heterotic M-theory with five-branes. We show that supersymmetry is still broken by a global mechanism and that the...
Holomorphic Vector Bundles and Non-Perturbative Vacua in M-Theory (1999)
Donagi, Ron, Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
We review the spectral cover formalism for constructing both U(n) and SU(n) holomorphic vector bundles on elliptically fibered Calabi-Yau three-folds which admit a section. We discuss the allowed...
Cosmology and Heterotic M-Theory in Five-Dimensions (1998)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
In these lectures, we present cosmological vacuum solutions of Horava-Witten theory and discuss their physical properties. We begin by deriving the five-dimensional effective action of strongly...
Non-Perturbative Vacua and Particle Physics in M-Theory (1998)
Donagi, Ron, Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
In this letter, we introduce a general theory for the construction of particle physics theories, with three families and realistic gauge groups, within the context of heterotic M-theory. This is...
Non-standard embedding and five-branes in heterotic M-Theory (1998)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
We construct vacua of M-theory on S^1/Z_2 associated with Calabi-Yau three-folds. These vacua are appropriate for compactification to N=1 supersymmetry theories in both four and five dimensions. We...
Heterotic M-theory in Five Dimensions (1998)
Lukas, Andre, Ovrut, Burt A., Stelle, K. S., Waldram, Daniel
We derive the five-dimensional effective action of strongly coupled heterotic string theory for the complete (1,1) sector of the theory by performing a reduction, on a Calabi-Yau three-fold, of...
Cosmological Solutions of Horava-Witten Theory (1998)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
We discuss simple cosmological solutions of Horava-Witten theory describing the strongly coupled heterotic string. At energies below the grand-unified scale, the effective theory is five- not...
The Universe as a Domain Wall (1998)
Lukas, Andre, Ovrut, Burt A., Stelle, K. S., Waldram, Daniel
It is shown that the effective five-dimensional theory of the strongly coupled heterotic string is a gauged version of N=1 five-dimensional supergravity with four-dimensional boundaries. For the...
The Cosmology of M-Theory and Type II Superstrings (1998)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
We review cosmological solutions of type II superstrings and M-theory, emphasizing the role of non-vanishing Ramond form backgrounds. Compactifications on flat and, more generally, maximally...
Gaugino Condensation in M-theory on S^1/Z_2 (1997)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
In the low energy limit of for M-theory on S^1/Z_2, we calculate the gaugino condensate potential in four dimensions using the background solutions due to Horava. We show that this potential is free...
On the Four-Dimensional Effective Action of Strongly Coupled Heterotic String Theory (1997)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
The low-energy D=4, N=1 effective action of the strongly coupled heterotic string is explicitly computed by compactifying Horava-Witten theory on the deformed Calabi-Yau three-fold solution due to...
On the D = 4, N = 2 Non-Renormalization Theorem (1997)
Buchbinder, Ioseph L., Kuzenko, Sergei M., Ovrut, Burt A.
Using the harmonic superspace background field formulation for general D=4, N=2 super Yang-Mills theories, with matter hypermultiplets in arbitrary representations of the gauge group, we present the...
Soliton Solutions of M-theory on an Orbifold (1997)
Lalak, Zygmunt, Lukas, Andre', Ovrut, Burt A.
We explicitly construct soliton solutions in the low energy description of M-theory on S^1/Z_2. It is shown that the 11-dimensional membrane is a BPS solution of this theory if stretched between the...
U-duality Covariant M-theory Cosmology (1997)
A manifestly U-duality covariant approach to M-theory cosmology is developed and applied to cosmologies in dimensions D=4,5. Cosmological properties such as expansion powers and Hubble parameters...
A Two-Form Formulation of the Vector-Tensor Multiplet in Central Charge Superspace (1997)
Buchbinder, Ioseph, Hindawi, Ahmed, Ovrut, Burt A.
A two-form formulation for the N=2 vector-tensor multiplet is constructed using superfield methods in central charge superspace. The N=2 non-Abelian standard supergauge multiplet in central charge...
U-Duality Symmetries from the Membrane Worldvolume (1997)
We study U-duality symmetries of toroidally compactified M theory from the membrane worldvolume point of view. This is done taking the most general set of bosonic background fields into account. Upon...
Membranes and Three-form Supergravity (1997)
Ovrut, Burt A., Waldram, Daniel
We discuss membranes in four-dimensional N=1 superspace. The kappa-invariance of the Green-Schwarz action implies that there is a dual version of N=1 supergravity with a three-form potential. We...
U-duality Covariant M-theory Cosmology (1997)
A manifestly U--duality covariant approach to M--theory cosmology is developed and applied to cosmologies in dimensions D = 4; 5. Cosmological properties such as expansion powers and Hubble...
Stabilizing dilaton and moduli vacua in string and M--Theory cosmology (1996)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
We show how non-trivial form fields can induce an effective potential for the dilaton and metric moduli in compactifications of type II string theory and M-theory. For particular configurations, the...
String and M-Theory Cosmological Solutions with Ramond Forms (1996)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
A general framework for studying a large class of cosmological solutions of the low-energy limit of type II string theory and of M-theory, with non-trivial Ramond form fields excited, is presented....
Vector-Tensor multiplet in N=2 superspace with central charge (1996)
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
We use the four-dimensional N=2 central charge superspace to give a geometrical construction of the Abelian vector-tensor multiplet consisting, under N=1 supersymmetry, of one vector and one linear...
Cosmological Solutions of Type II String Theory (1996)
Lukas, Andre, Ovrut, Burt A., Waldram, Daniel
We study cosmological solutions of type II string theory with a metric of the Kaluza--Klein type and nontrivial Ramond--Ramond forms. It is shown that models with only one form excited can be...
Higher-Derivative Gravity in String Theory (1996)
Forger, Kristin, Ovrut, Burt A., Theisen, Stefan J., Waldram, Daniel
We explicitly extract the structure of higher-derivative curvature-squared terms at genus 0 and 1 in the d=4 heterotic string effective action compactified on symmetric orbifolds by computing...
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
We show how spontaneous supersymmetry breaking in the vacuum state of higher-derivative supergravity is transmitted, as explicit soft supersymmetry-breaking terms, to the effective Lagrangian of the...
Higher-derivative gravity in string theory (1996)
Förger, Kristin, Ovrut, Burt A., Theisen, Stefan, Waldram, Daniel
We explicitly extract the structure of higher-derivative curvature-squared terms at genus 0 and 1 in the d = 4 heterotic string effective action compactified on symmetric orbifolds by computing...
Four-Dimensional Higher-Derivative Supergravity and Spontaneous Supersymmetry Breaking (1995)
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
We construct two classes of higher-derivative supergravity theories generalizing Einstein supergravity. We explore their dynamical content as well as their vacuum structure. The first class is found...
Two-Dimensional Higher-Derivative Supergravity and a New Mechanism for Supersymmetry Breaking (1995)
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
We discuss the general form of quadratic (1,1) supergravity in two dimensions, and show that this theory is equivalent to two scalar supermultiplets coupled to non-trivial supergravity. It is...
Non-Trivial Vacua in Higher-Derivative Gravitation (1995)
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
A discussion of an extended class of higher-derivative classical theories of gravity is presented. A procedure is given for exhibiting the new propagating degrees of freedom, at the full non-linear...
Consistent Spin-Two Coupling and Quadratic Gravitation (1995)
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
A discussion of the field content of quadratic higher-derivative gravitation is presented, together with a new example of a massless spin-two field consistently coupled to gravity. The full quadratic...
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
A discussion of the number of degrees of freedom, and their dynamical properties, in higher derivative gravitational theories is presented. The complete non-linear sigma model for these degrees of...
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
A discussion of the number of degrees of freedom, and their dynamical properties, in higher derivative gravitational theories is presented. The complete non-linear sigma model for these degrees of...
Higher-Derivative Gravitation in Bosonic and Superstring Theories (1995)
Hindawi, Ahmed, Ovrut, Burt A., Waldram, Daniel
A discussion of the number of degrees of freedom, and their dynamical properties, in higher-derivative gravitational theories is presented. The complete non-linear sigma model for these degrees of...
Higher Derivative Gravitation in Superstrings (1995)
A discussion of the number of degrees of freedom, and their dynamical properties, in higher derivative gravitational theories is presented. It is shown that non-vanishing $(C_{mnpq})^{2}$ terms arise...
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...
Supersymmetric Calculation of Mixed K\"{a}HLER-Gauge and Mixed K\"{a}HLER-Lorentz Anomalies (1993)
Cardoso, Gabriel Lopes, Ovrut, Burt A.
We present a manifestly supersymmetric procedure for calculating the contributions from matter loops to the mixed K\"{a}hler-gauge and to the mixed K\"{a}hler- Lorentz anomalies in $N=1, D=4$...
Natural Supergravity Inflation (1992)
Cardoso, Gabriel Lopes, Ovrut, Burt A.
We show that a single uncharged chiral superfield, canonically coupled to \mbox{$N=1$} supergravity with vanishing superpotential, naturally drives inflation in the early universe for a class of...
Cardoso, Gabriel Lopes, Ovrut, Burt A.
We discuss the complete set of one-loop triangle graphs involving the Yang-Mills gauge connection, the \Kahler\ connection and the $\sigma$-model coordinate connection in the effective field theory...
THE ANOMALY STRUCTURE OF (2, 0) HETEROTIC WORLDSHEET SUPERGRAVITY WITH GAUGED R-INVARIANCE (1992)
Suresh Govindarajan, Burt A. Ovrut
We present a superfield approach to the theory of (2, 0) worldsheet supergravity. The (2, 0) structure group is enlarged to Lorentz ×U(1) and the anomaly structure of this ex-tended theory is...
Suresh Govindarajan, Burt A. Ovrut
We present a geometric interpretation for the torsion constraints in (2, 0) supergravity using G-structures. This leads to a classification of the constraints as given by [1]. We also present the...
The locally supersymmetric geometrical hierarchy model (1983)
We examine the locally supersymmetric geometrical hierarchy model at energies below the unification mass, MGU. The superfield content, for which the theory has acceptable values of MGU and...
The geometrical hierarchy model and N = 1 supergravity (1983)
We incorporate the geometrical hierarchy model of Dimopoulos and Raby into N = 1 supergravity. Supersymmetry is spontaneously broken at a scale of order 1011 GeV and the cosmological constant is fine...
Supergravity and the inverted gauge hierarchy (1983)
We generalize a class of O'Raifeartaigh models with Witten's inverted gauge hierarchy to N = 1 supergravity. Radiative corrections induce a grand unification scale that is several orders of magnitude...