Results for "Mirjam Walloth"

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Residual-type A Posteriori Estimators for a Singularly Perturbed Reaction-Diffusion Variational Inequality -- Reliability, Efficiency and RobustnessDec 05 2018We derive a new residual-type a posteriori estimator for a singularly perturbed reaction-diffusion problem with obstacle constraints. It generalizes robust residual estimators for unconstrained singularly perturbed equations. The robust upper and local ... More
Mesh adaptivity for quasi-static phase-field fractures based on a residual-type a posteriori error estimatorJun 11 2019In this work, we consider adaptive mesh refinement for a monolithic phase-field description for fractures in brittle materials. Our approach is based on an a posteriori error estimator for the phase-field variational inequality realizing the fracture ... More
Ordinary and Dilatonic Domain Walls: Solutions and Induced Space-TimesJun 02 1993Recent developments in unifying treatment of domain wall configurations and their global space-time structure is presented. Domain walls between vacua of non-equal cosmological constant fall in three classes depending on the value of their energy density ... More
Flat World of Dilatonic Domain WallsApr 16 1993We study dilatonic domain walls specific to superstring theory. Along with the matter fields and metric the dilaton also changes its value in the wall background. We found supersymmetric (extreme) solutions which in general interpolate between isolated ... More
Stability of Vacua and Domain Walls in Supergravity and Superstring TheoryOct 01 1992We address the possibility of false vacuum decay in $N=1$ supergravity theories, including those corresponding to superstring vacua. By establishing a Bogomol'nyi bound for the energy density stored in the domain wall of the $O(4)$ invariant bubble, we ... More
Stringy Domain Walls and Other Stringy Topological DefectsFeb 19 1992We point out that the moduli sector of the $(2,2)$ string compactification with its nonperturbatively preserved non-compact symmetries is a framework to study global topological defects. Based on the target space modular invariance of the nonperturbative ... More
Properties of Black Holes in Toroidally Compactified String TheoryJan 28 1997We review the macroscopic and microscopic properties of black holes of toroidally compactified heterotic and Type II string theory in dimensions 4<=D<=9. General charged rotating black hole solutions are obtained by acting on a generating solution with ... More
Extreme Domain Wall--Black Hole Complementarity in N=1SUPERGRAVITY with a General Dilaton CouplingFeb 16 1994Oct 20 1994We study supersymmetric (extreme) domain walls in four-dimensional (4d) N=1 supergravity theories with a general dilaton coupling $\alpha > 0$. Type I walls, which are static, planar (say, in ($x,y$) plane) configurations, interpolate between Minkowski ... More
Supergravity Walls as Windows into New Types of VacuaDec 23 1993Jan 02 1994Within four dimensional (4d) N=1 supergravity theories we present extreme dilatonic domain wall solutions with a general overall coupling $\alpha$ in the dilaton K\" ahler potential. We concentrate on extreme Type I walls, which are static, planar configurations, ... More
Quantum Causal Structure and Quantum ThermodynamicsJul 17 2018This thesis reports progress in two domains, causal structures and microscopic thermodynamics, both of which are pertinent in the development of quantum technologies. The first part is dedicated to the analysis of causal structure, which encodes the relationship ... More
Stringy Origin of Neutrino Masses within the Minimal Supersymmetric Standard ModelOct 01 1992We present a ``gravity-induced'' seesaw mechanism, which accommodates neutrino masses ($m_\nu\propto m_u^2/M_I$, with $m_u$ the corresponding quark mass and $M_I\simeq 4\times10^{11}$ GeV) compatible with the MSW study of the Solar neutrino deficit within ... More
Weak braided monoidal categories and their homotopy colimitsOct 24 2014We show that the homotopy colimit construction for diagrams of categories with an operad action, recently introduced by Fiedorowicz, Stelzer and Vogt, has the desired homotopy type for diagrams of weak braided monoidal categories. This provides a more ... More
Microscopics of Rotating Black Holes: Entropy and Greybody FactorsOct 19 1998Oct 20 1998We review the status of microscopic counting of rotating black hole degrees of freedom. We present two complementary approaches which both utilize the near-horizon geometry and precisely reproduce the Bekenstein Hawking entropy for near-extreme rotating ... More
Supersymmetric Intersecting D6-branes and Fluxes in Massive Type IIA String TheoryAug 06 2003Nov 06 2003We study N=1 supersymmetric four-dimensional solutions of massive Type IIA supergravity with intersecting D6-branes in the presence NS-NS three-form fluxes. We derive N=1 supersymmetry conditions for the D6-brane and flux configurations in an internal ... More
General N = 1 Supersymmetric Fluxes in Massive Type IIA String TheoryJul 29 2004Aug 17 2004We study conditions on general fluxes of massive Type IIA supergravity that lead to four-dimensional backgrounds with N = 1 supersymmetry. We derive these conditions in the case of SU(3)- as well as SU(2)-structures. SU(3)-structures imply that the internal ... More
Gauging of N=2 Supergravity Hypermultiplet and Novel Renormalization Group FlowsJan 01 2001Jun 28 2001We provide the explicit gauging of all the SU(2,1) isometries of one N=2 supergravity hypermultiplet, which spans SU(2,1)/U(2) coset space parameterized in terms of two complex projective coordinate fields z_1 and z_2. We derive the full, explicit Killing ... More
D=4 N=1 Type IIB Orientifolds with Continuous Wilson Lines, Moving Branes, and their Field Theory RealizationJun 06 2000We investigate four-dimensional N=1 Type IIB orientifolds with continuous Wilson lines, and their T-dual realizations as orientifolds with moving branes. When continuous Wilson lines become discrete the gauge symmetry is enhanced and the T-dual orientifold ... More
Signatures for Heavy $\bf Z'$ Bosons at Hadron CollidersOct 08 1992We discuss three promising diagnostic probes of the couplings of a possible heavy $Z'$ boson at hadron colliders: the forward-backward asymmetry into leptons, the rare decay $Z' \ra W^{\pm} \ell^{\mp} \nu$, and associated production $pp \ra Z'W,\; Z'Z$. ... More
$V'Z$ and $V'W$ Production as Tests of Heavy Gauge Boson Couplings at Future Hadron CollidersJul 05 1992We point out that the production cross section of $pp\to V'V$, with $V'=W',Z'$ and $V=W,Z$ is a useful diagnostic of $V'$ gauge couplings at future hadron colliders. For $M_{Z'}\simeq1$ TeV it would allow determination of combinations of $Z'$ gauge couplings ... More
BPS Saturated and Non-Extreme States in Abelian Kaluza-Klein Theory and Effective N=4 Supersymmetric String VacuaAug 14 1995We summarize results for all four-dimensional Bogomol'nyi-Sommerfield-Prasat (BPS) saturated and non-extreme solutions of the ($4+n$)-dimensional Abelian Kaluza-Klein theory. Within effective N=4 supersymmetric string vacua, parameterized in terms of ... More
Non-Shannon inequalities in the entropy vector approach to causal structuresMay 06 2016Mar 11 2018A causal structure is a relationship between observed variables that in general restricts the possible correlations between them. This relationship can be mediated by unobserved systems, modelled by random variables in the classical case or joint quantum ... More
Hierarchies from D-brane instantons in globally defined Calabi-Yau OrientifoldsNov 02 2007Aug 14 2008We construct the first globally consistent semi-realistic Type I string vacua on an elliptically fibered manifold where the zero modes of the Euclidean D1-instanton sector allow for the generation of non-perturbative Majorana masses of an intermediate ... More
General Rotating Black Holes in String Theory: Greybody Factors and Event HorizonsMay 26 1997Aug 14 1997We derive the wave equation for a minimally coupled scalar field in the background of a general rotating five-dimensional black hole. It is written in a form that involves two types of thermodynamic variables, defined at the inner and outer event horizon, ... More
TASI Lectures on Abelian and Discrete Symmetries in F-theoryAug 31 2018Nov 11 2018In F-theory compactifications, the abelian gauge sector is encoded in global structures of the internal geometry. These structures lie at the intersection of algebraic and arithmetic description of elliptic fibrations: While the Mordell--Weil lattice ... More
Gravity Trapping on a Finite Thickness Domain Wall: An Analytic StudyJan 07 2008We construct an explicit model of gravity trapping domain wall potential where for the first time we can study explicitly the graviton wave function fluctuations for any thickness of the domain wall. A concrete form of the potential depends on one parameter ... More
Conformal Invariance and Near-extreme Rotating AdS Black HolesJun 21 2011Aug 07 2011We obtain retarded Green's functions for massless scalar fields in the background of near-extreme, near-horizon rotating charged black holes of five-dimensional minimal gauged supergravity. The radial part of the (separable) massless Klein-Gordon equation ... More
An Analysis of the Wave Equation for the $U(1)^{2}$ Gauged Supergravity Black HoleJan 13 2015Mar 31 2015We study the massless Klein-Gordon equation in the background of the most general rotating dyonic AdS black hole in gauged $\mathcal{N}=2$, $U(1)^{2}$ gauged supergravity in $D=4$, given by Chow and Comp\`{e}re [Phys. Rev. D\textbf{89} (2014) 065003]. ... More
D-Instanton Generated Dirac Neutrino MassesMar 19 2008Sep 16 2008We present a stringy mechanism to generate Dirac neutrino masses by D-instantons in an experimentally relevant mass scale without fine-tuning. Within Type IIA string theory with intersecting D6-branes, we spell out specific conditions for the emergence ... More
New Gauge Bosons from String ModelsFeb 29 1996We address the mass ranges of new neutral gauge bosons and constraints on the accompanying exotic particles as predicted by a class of superstring models. Under certain assumptions about the supersymmetry breaking parameters we show that breaking of an ... More
Implications of Abelian Extended Gauge Structures From String ModelsNov 21 1995Nov 28 1995Within a class of superstring vacua which have an additional non-anomalous $U(1)'$ gauge factor, we address the scale of the $U(1)'$ symmetry breaking and constraints on the exotic particle content and their masses. We also show that an extra gauge $U(1)'$ ... More
Entropy of Non-Extreme Charged Rotating Black Holes in String TheoryMar 22 1996Jun 11 1996We give the explicit expression for four-dimensional rotating charged black hole solutions of N=4 (or N=8) superstring vacua, parameterized by the ADM mass, four charges (two electric and two magnetic charges, each arising from a different U(1) gauge ... More
Four-dimensional supersymmetric dyonic black holes in eleven-dimensional supergravityMay 08 1995A class of 4-dimensional supersymmetric dyonic black hole solutions that arise in an effective 11-dimensional supergravity compactified on a 7-torus is presented. We give the explicit form of dyonic solutions with diagonal internal metric, associated ... More
AdS$_2$ Holographic DictionaryAug 25 2016Jan 23 2017We construct the holographic dictionary for both running and constant dilaton solutions of the 2D Einstein-Maxwell-Dilaton theory obtained by a circle reduction from 3D gravity with negative cosmological constant. This specific model ensures that the ... More
More Supersymmetric Standard-like Models from Intersecting D6-branes on Type IIA OrientifoldsMar 24 2003We present new classes of supersymmetric Standard-like models from type IIA $\IT^6/(\IZ_2\times \IZ_2)$ orientifold with intersecting D6-branes. D6-branes can wrap general supersymmetric three-cycles of $\IT^6=\IT^2\times \IT^2\times \IT^2$, and any $\IT^2$ ... More
Duality Invariant Non-Extreme Black Holes in Toroidally Compactified String TheoryMar 19 1997Apr 02 1997We present duality invariant structure of the thermodynamic quantities of non-extreme black hole solutions of torodially compactified Type II (M-theory) and heterotic string in five and four dimensions. These quantities are parameterized by duality invariant ... More
General relation between Aretakis charge and Newman-Penrose chargeNov 14 2018Nov 25 2018We reexamine the relation between the Aretakis charge of an extremal black hole spacetime and the Newman-Penrose charge of a weakly asymptotically flat spacetime obtained from the original one through radial inversion and conformal mapping. Building on ... More
AdS$_2$ Holographic DictionaryAug 25 2016We construct the holographic dictionary for both running and constant dilaton solutions of the 2D Einstein-Maxwell-Dilaton theory obtained by a circle reduction from 3D gravity with negative cosmological constant. This specific model ensures that the ... More
Anti-deSitter Vacua of Gauged Supergravities with 8 SuperchargesJan 24 2000We investigate supersymmetric extrema of Abelian gauged supergravity theories with non-trivial vector multiplets and 8 supercharges in four and five dimensions. The scalar fields of these models parameterize a manifold consisting of disconnected branches ... More
Rotating Intersecting M-BranesDec 24 1996Jun 06 1997We present intersecting p-brane solutions of eleven-dimensional supergravity (M-branes) which upon toroidal compactification reduce to non-extreme ``rotating'' black holes. We identify harmonic functions, associated with each M-brane, and non-extremality ... More
KALUZA-KLEIN BLACK HOLES WITHIN HETEROTIC STRING THEORY ON A TORUSFeb 20 1995We point out that in heterotic string theory compactified on a 6-torus, after a consistent truncation of the 10-d gauge fields and the antisymmetric tensor fields, 4-dimensional black holes of Kaluza-Klein theory on a 6-torus constitute a subset of solutions. ... More
General Static Spherically Symmetric Black Holes of Heterotic String on a Six TorusDec 18 1995Apr 22 1996We present the most general static, spherically symmetric solutions of heterotic string compactified on a six-torus that conforms to the conjectured ``no-hair theorem'', by performing a subset of O(8,24) transformations, i.e., symmetry transformations ... More
Cosmic Censorship Violation for a Class of Supersymmetric SolitonsNov 30 1993Dec 01 1993We study vacuum domain walls in a class of four-dimensional $N=1$ supergravity theories where along with the matter field, forming the wall, there is more than one ``dilaton'', each respecting $SU(1,1)$ symmetry in their sub-sector. We find {\it supersymmetric} ... More
Analysing causal structures in generalised probabilistic theoriesDec 11 2018Causal structures give us a way to understand the origin of observed correlations. These were developed for classical scenarios, but quantum mechanical experiments necessitate their generalisation. Here we study causal structures in a broad range of theories, ... More
Inability of the entropy vector method to certify nonclassicality in linelike causal structuresMar 08 2016Oct 18 2016Bell's theorem shows that our intuitive understanding of causation must be overturned in light of quantum correlations. Nevertheless, quantum mechanics does not permit signalling and hence a notion of cause remains. Understanding this notion is not only ... More
Greybody Factors for Black Holes in Four Dimensions: Particles with SpinDec 11 1997We compute the emission spectrum of minimally coupled particles with spin that are Hawking radiated from four dimensional black holes in string theory. For a range of the black hole parameters the result has a product structure that may be interpreted ... More
Infra-red fixed points at the boundaryFeb 07 2000Gauged supergravities (in four and five dimensions) with eight supercharges and with vector supermultiplets have a unique ultra-violet (UV) fixed point on a given physical domain \cal M of the space of the scalar fields. We show that in these models the ... More
Supersymmetric Standard Models, Flux Compactification and Moduli StabilizationSep 02 2004Jan 21 2005Based on the T-dual constructions of supersymmetric intersecting D6-models on Z_2 x Z_2 orientifolds, whose electroweak sector is parallel with the orientifold planes with Sp(2f)_L x Sp(2f)_R gauge symmetry (hep-th/0407178), we derive and classify Standard ... More
New Grand Unified Models with Intersecting D6-branes, Neutrino Masses, and Flipped SU(5)Jul 31 2006Aug 01 2006We construct new supersymmetric SU(5) Grand Unified Models based on Z4 x Z2 orientifolds with intersecting D6-branes. Unlike constructions based on Z2 x Z2 orientifolds, the orbifold images of the three-cycles wrapped by D6-branes correspond to new configurations ... More
Neutrino Masses within the Minimal Supersymmetric Standard ModelMay 13 1992May 18 1992We investigate the possibility of accommodating neutrino masses compatible with the MSW study of the Solar neutrino deficit within the minimal supersymmetric Standard Model. The ``gravity-induced'' seesaw mechanism based on an interplay of nonrenormalizable ... More
Non-Shannon inequalities in the entropy vector approach to causal structuresMay 06 2016Oct 01 2016A causal structure is a relationship between observed variables that in general restricts the set of possible correlations between them. This relationship can be mediated by unobserved systems, which correspond to random variables in the classical case ... More
TASI Lectures: Particle Physics from Perturbative and Non-perturbative Effects in D-braneworldsJan 14 2011Jan 22 2011In these notes we review aspects of semi-realistic particle physics from the point of view of type II orientifold compactifications. We discuss the appearance of gauge theories on spacetime filling D-branes which wrap non-trivial cycles in the Calabi-Yau. ... More
Near-BPS-Saturated Rotating Electrically Charged Black Holes as String StatesMay 08 1996We construct generating solutions for general D-dimensional ($4 \le D \le 9$) rotating, electrically charged, black holes in the effective action of toroidally compactified heterotic (or Type IIA) string. The generating solution is parameterized by the ... More
General Rotating Five Dimensional Black Holes of Toroidally Compactified Heterotic StringMar 15 1996Jul 04 1996We present the most general rotating black hole solution of five-dimensional N=4 superstring vacua that conforms to the ``no hair theorem''. It is chosen to be parameterized in terms of massless fields of the toroidally compactified heterotic string. ... More
Addendum to Supersymmetric Dyonic Black Holes in Kaluza-Klein TheoryMar 12 1995We complete the study of 4-dimensional (4-d), static, spherically symmetric, supersymmetric black holes (BH's) in Abelian $(4+n)$-d Kaluza-Klein theory, by showing that for such solutions $n$ electric charges $\vec{\cal Q} \equiv (Q_1,...,Q_n)$ and $n$ ... More
Bent BPS domain walls of D=5 N=2 gauged supergravity coupled to hypermultipletsJan 31 2002Within D=5 N=2 gauged supergravity coupled to hypermultiplets we derive consistency conditions for BPS domain walls with constant negative curvature on the wall. For such wall solutions to exist, the covariant derivative of the projector, governing the ... More
Conformal Symmetry for General Black HolesJun 16 2011We show that the warp factor of a generic asymptotically flat black hole in five dimensions can be adjusted such that a conformal symmetry emerges. The construction preserves all near horizon properties of the black holes, such as the thermodynamic potentials ... More
Conformal Symmetry for Black Holes in Four DimensionsDec 20 2011Jul 02 2012We show that the asymptotic boundary conditions of general asymptotically flat black holes in four dimensions can be modified such that a conformal symmetry emerges. The black holes with the asymptotic geometry removed in this manner satisfy the equations ... More
Greybody Factors and Charges in Kerr/CFTAug 10 2009Aug 13 2009We compute greybody factors for near extreme Kerr black holes in D=4 and D=5. In D=4 we include four charges so that our solutions can be continuously deformed to the BPS limit. In D=5 we include two independent angular momenta so Left-Right symmetry ... More
Microstates of Four-Dimensional Rotating Black Holes from Near-Horizon GeometryMay 21 1998We show that a class of four-dimensional rotating black holes allow five-dimensional embeddings as black rotating strings. Their near-horizon geometry factorizes locally as a product of the three-dimensional anti-deSitter space-time and a two-dimensional ... More
Wave Equation for the Wu Black HoleJul 30 2014Sep 25 2014Wu black hole is the most general solution of maximally supersymmetric gauged supergravity in D=5, containing $U(1)^{3}$ gauge symmetry. We study the separability of the massless Klein-Gordon equation and probe its singularities for a general stationary, ... More
Addentum to: Conformal Invariance and Near-extreme Rotating AdS Black HolesJun 19 2014Sep 13 2014We obtained retarded Green's functions for massless scalar fields in the background of near-extreme, near-horizon rotating charged black hole of five-dimensional minimal gauged supergravity in Phys. Rev. D84, 044018 (2011). For general nonextreme black ... More
Vacuum polarization throughout general subtracted black hole spacetimesDec 20 2016May 09 2017We compute the vacuum polarization of a massless minimally co pled scalar field in a background given by a black hole with subtracted geometry. Extending previous results for the horizon of rotating black holes with no charge, we obtain an analytical ... More
Vacuum Domain Walls in D-dimensions: Local and Global Space-Time StructureDec 21 1999We study local and global gravitational effects of (D-2)-brane configurations (domain-walls) in the vacuum of D-dimensional space-time. We focus on infinitely thin vacuum domain walls with arbitrary cosmological constants on either side of the wall. In ... More
Supersymmetric Domain-Wall World from D=5 Simple Gauged SupergravitySep 10 1999Oct 05 1999We address a supersymmetric embedding of domain walls with asymptotically anti-deSitter (AdS) space-times in five-dimensional simple, N=2 U(1) gauged supergravity theory constructed by Gunaydin, Townsend and Sierra. These conformally flat solutions interpolate ... More
General N = 1 Supersymmetric Flux Vacua of (Massive) Type IIA String TheoryMar 03 2004We derive conditions for the existence of four-dimensional \N=1 supersymmetric flux vacua of massive type IIA string theory with general supergravity fluxes turned on. For an SU(3) singlet Killing spinor, we show that such flux vacua exist only when the ... More
Time-dependent backgrounds from supergravity with gauged non-compact R-symmetryMar 31 2003Apr 05 2003We obtain a general class of time-dependent, asymptotically de Sitter backgrounds which solve the first order bosonic equations that extremize the action for supergravity with gauged non-compact $R$-symmetry. These backgrounds correspond only to neutral ... More
BPS-Saturated Bound States of Tilted P-Branes in Type II String TheoryFeb 28 1997Jun 24 1997We found BPS-saturated solutions of M-theory and Type II string theory which correspond to (non-marginally) bound states of p-branes intersecting at angles different from pi/2. These solutions are obtained by starting with a BPS marginally bound (orthogonally) ... More
BPS Saturated Dyonic Black Holes of $N=8$ Supergravity VacuaOct 16 1995Oct 16 1995We summarize the results for four-dimensional Bogomol'nyi-Prasad- Sommerfield (BPS) saturated dyonic black hole solutions arising in the Kaluza-Klein sector and the three-form field sector of the eleven-dimensional supergravity on a seven-torus. These ... More
Singular BPS Saturated States and Enhanced Symmetries of Four-Dimensional N=4 Supersymmetric String VacuaJul 31 1995Aug 24 1995A class of supersymmetric (BPS saturated), static, spherically symmetric solutions of four-dimensional effective N=4 supersymmetric superstring vacua, which become massless at special points of moduli space, is studied in terms of the fields of the effective ... More
Dyonic BPS Saturated Black Holes of Heterotic String on a Six-TorusJul 18 1995Nov 05 1995Within effective heterotic superstring theory compactified on a six-torus we derive minimum energy (supersymmetric), static, spherically symmetric solutions, which are manifestly invariant under the target space $O(6,22)$ and the strong-weak coupling ... More
All the Four Dimensional Static, Spherically Symmetric Solutions of Abelian Kaluza-Klein TheoryMar 12 1995Nov 05 1995We present the explicit form for all the four dimensional, static, spherically symmetric solutions in $(4+n)$-d Abelian Kaluza-Klein theory by performing a subset of $SO(2,n)$ transformations corresponding to four $SO(1,1)$ boosts on the Schwarzschild ... More
STATIC FOUR-DIMENSIONAL ABELIAN BLACK HOLES IN KALUZA-KLEIN THEORYFeb 16 1995Static, four-dimensional (4-d) black holes (BH's) in ($4+n$)-d Kaluza-Klein (KK) theory with Abelian isometry and diagonal internal metric have at most one electric ($Q$) and one magnetic ($P$) charges, which can either come from the same $U(1)$-gauge ... More
Supersymmetric Dyonic Black Holes in Kaluza-Klein TheorySep 20 1994We study supersymmetric, four-dimensional (4-d), Abelian charged black holes (BH's) arising in (4+n)-d (1 \le n \le 7) Kaluza-Klein (KK) theories. Such solutions, which satisfy supersymmetric Killing spinor equations (formally satisfied for any n) and ... More
Conformal Field Theory Couplings for Intersecting D-branes on OrientifoldsMar 10 2003May 17 2004We present a conformal field theory calculation of four-point and three-point correlation functions for the bosonic twist fields arising at the intersections of D-branes wrapping (supersymmetric) homology cycles of Type II orientifold compactifications. ... More
Proton decay via dimension-six operators in intersecting D6-brane modelsJun 01 2006Aug 04 2006We analyze the proton decay via dimension six operators in supersymmetric SU(5)-Grand Unified models based on intersecting D6-brane constructions in Type IIA string theory orientifolds. We include in addition to 10* 10 10* 10 interactions also the operators ... More
Analysing causal structures with entropySep 26 2017Jul 25 2018A central question for causal inference is to decide whether a set of correlations fit a given causal structure. In general, this decision problem is computationally infeasible and hence several approaches have emerged that look for certificates of compatibility. ... More
Analysing causal structures in generalised probabilistic theoriesDec 11 2018Aug 11 2019Causal structures give us a way to understand the origin of observed correlations. These were developed for classical scenarios, but quantum mechanical experiments necessitate their generalisation. Here we study causal structures in a broad range of theories, ... More
Domain Walls in $N=1$ SupergravitySep 28 1992Oct 08 1992We discuss a study of domain walls in $N=1, d=4$ supergravity. The walls saturate the Bogomol'nyi bound of wall energy per unit area thus proving stability of the classical solution. They interpolate between two vacua whose cosmological constant is non-positive ... More
A string theoretic model of gauge mediated supersymmetry beakingJul 25 2008Aug 19 2008We propose a robust supergravity model of dynamical supersymmetry breaking and gauge mediation, and a natural embedding in non-perturbative string theory with D-branes. A chiral field (and its mirror) charged under "anomalous" U(1)'s acts as a Polonyi ... More
Black Holes with Intrinsic SpinJun 17 2014We analyze the general black hole solutions to the four dimensional STU model recently constructed by Chow and Compere. We define a dilute gas limit where the black holes can be interpreted as excited states of an extremal ground state. In this limit ... More
Near Horizon Geometry of Rotating Black Holes in Five DimensionsMay 18 1998We interpret the general rotating black holes in five dimensions as rotating black strings in six dimensions. In the near horizon limit the geometry is locally AdS_3 x S_3, as in the nonrotating case. However, the global structure couples the AdS_3 and ... More
Black Hole Horizons and the Thermodynamics of StringsAug 16 1997Sep 03 1997We review the classical thermodynamics and the greybody factors of general (rotating) non-extreme black holes and discuss universal features of their near-horizon geometry. We motivate a microscopic interpretation of general black holes that relates the ... More
Greybody factors for rotating black holes in four dimensionsJun 10 1997Aug 14 1997We present the wave equation for a minimally coupled scalar field in the background of a rotating four-dimensional black hole that is parametrized by its mass, angular momentum, and four independent U(1) charges. The near horizon structure is identical ... More
The Global Gauge Group Structure of F-theory Compactification with U(1)sJun 26 2017Jan 22 2018We show that F-theory compactifications with abelian gauge factors generally exhibit a non-trivial global gauge group structure. The geometric origin of this structure lies with the Shioda map of the Mordell--Weil generators. This results in constraints ... More
Braided injections and double loop spacesMar 05 2014Dec 15 2015We consider a framework for representing double loop spaces (and more generally E-2 spaces) as commutative monoids. There are analogous commutative rectifications of braided monoidal structures and we use this framework to define iterated double deloopings. ... More
Non-threshold D-brane bound states and black holes with non-zero entropyMar 28 1997Jul 14 1997We start with BPS-saturated configurations of two (orthogonally) intersecting M-branes and use the electro-magnetic duality or dimensional reduction along a boost, in order to obtain new p-brane bound states. In the first case the resulting configurations ... More
Massless BPS-Saturated States on the Two-Torus Moduli Sub-Space of Heterotic StringDec 22 1995Feb 29 1996Within a four-dimensional, toroidally compactified heterotic string, we identify (quantized) charge vectors of electrically charged BPS-saturated states (along with the tower of SL(2,Z) related dyonic states), which preserve 1/2 of N=4 supersymmetry and ... More
Phases of R-charged Black Holes, Spinning Branes and Strongly Coupled Gauge TheoriesFeb 25 1999We study the thermodynamic stability of charged black holes in gauged supergravity theories in D=5, D=4 and D=7. We find explicitly the location of the Hawking-Page phase transition between charged black holes and the pure anti-de Sitter space-time, both ... More
Supergravity Domain WallsApr 16 1996We review the status of domain walls in $N=1$ supergravity theories for both the vacuum domain walls as well as dilatonic domain walls. We concentrate on a systematic analysis of the nature of the space-time in such domain wall backgrounds and the special ... More
Thermodynamic Stability and Phases of General Spinning BranesMar 16 1999Jul 29 1999We determine the thermodynamic stability conditions for near-extreme rotating D3, M5, and M2-branes with multiple angular momenta. Critical exponents near the boundary of stability are discussed and compared with a naive field theory model. From a partially ... More
Black Holes and U-DualityJun 28 1996Nov 04 1996We find the general charged rotating black hole solutions of the maximal supergravities in dimensions $4\le D\le 9$ arising from toroidally compactified Type II string or M-theories. In each dimension, these are obtained by acting on a generating solution ... More
Criteria for assessing grant applications: A systematic reviewAug 04 2019Criteria are an essential component of any procedure for assessing merit. Yet, little is known about the criteria peers use in assessing grant applications. In this systematic review we therefore identify and synthesize studies that examine grant peer ... More
Wrapped Branes and SupersymmetrySep 03 1997Nov 24 1997Configurations of two or more branes wrapping different homology cycles of space-time are considered and the amount of supersymmetry preserved is analysed, generalising the analysis of multiple branes in flat space. For K3 compactifications, these give ... More
Naked singularities in dilatonic domain wall space-timesNov 23 1994We investigate gravitational effects of extreme, non-extreme and ultra- extreme domain walls in the presence of a dilaton field. The dilaton is a scalar field without self-interaction that couples to the matter po- tential that is responsible for the ... More
Fooling-sets and rank in nonzero characteristic (extended abstract)May 02 2013An n\times n matrix M is called a fooling-set matrix of size n, if its diagonal entries are nonzero, whereas for every k\ne \ell we have M_{k,\ell} M_{\ell,k} = 0. Dietzfelbinger, Hromkovi\v{c}, and Schnitger (1996) showed that n \le (\rk M)^2, regardless ... More
Solitonic Strings and BPS Saturated Dyonic Black HolesDec 06 1995Nov 05 1996We consider a six-dimensional solitonic string solution described by a conformal chiral null model with non-trivial $N=4$ superconformal transverse part. It can be interpreted as a five-dimensional dyonic solitonic string wound around a compact fifth ... More
Supersymmetric Pati-Salam Models from Intersecting D6-branes: A Road to the Standard ModelMar 05 2004Oct 11 2004We provide a systematic construction of three-family N=1 supersymmetric Pati-Salam models from Type IIA orientifolds on $\IT^6/(\IZ_2\times \IZ_2)$ with intersecting D6-branes. All the gauge symmetry factors $SU(4)_C\times SU(2)_L \times SU(2)_R$ arise ... More
Dynamical Supersymmetry Breaking in Standard-like Models with Intersecting D6-branesMar 24 2003We address dynamical supersymmetry breaking within a N=1 supersymmetric Standard-like Model based on a Z_2 x Z_2 Type IIA orientifold with intersecting D6-branes. The model possesses an additional, confining gauge sector with the USp(2)_A x USp(2)_B x ... More
Effects of Heavy States on the Effective N=1 Supersymmetric ActionJul 09 1998Using the power of superspace formalism, we investigate the decoupling effects of heavy states in N=1 supersymmetric field theory. We find that "mixed" couplings in the superpotential between the heavy and light fields contribute to the effective superpotential ... More
Entanglement entropy of subtracted geometry black holesJul 01 2014Jul 03 2014We compute the entanglement entropy of minimally coupled scalar fields on subtracted geometry black hole backgrounds, focusing on the logarithmic corrections. We notice that matching between the entanglement entropy of original black holes and their subtracted ... More