Spherically symmetric spacetimes in massive gravity (2002)
Damour, Thibault, Kogan, Ian I., Papazoglou, Antonios
We explore spherically symmetric stationary solutions, generated by ``stars'' with regular interiors, in purely massive gravity. We reexamine the claim that the resummation of non-linear effects can...
Ghost-Matter Mixing and Feigenbaum Universality in String Theory (2002)
Kogan, Ian I., Polyakov, Dimitri
Brane-like vertex operators, defining backgrounds with the ghost-matter mixing in NSR superstring theory, play an important role in a world-sheet formulation of D-branes and M theory, being creation...
DBI Action from Closed Strings and D-brane second Quantization (2002)
Kogan, Ian I., Polyakov, Dimitri
Brane-like vertex operators play an important role in a worldsheet formulation of D-branes and M-theory. In this paper we derive the DBI D-brane action from NSR closed string sigma-model with...
Effective Lagrangians and Universality Classes of Nonlinear Bigravity (2002)
Damour, Thibault, Kogan, Ian I.
We discuss the fully non-linear formulation of multigravity. The concept of universality classes of effective Lagrangians describing bigravity, which is the simplest form of multigravity, is...
Non-linear bigravity and cosmic acceleration (2002)
Damour, Thibault, Kogan, Ian I., Papazoglou, Antonios
We explore the cosmological solutions of classes of non-linear bigravity theories. These theories are defined by effective four-dimensional Lagrangians describing the coupled dynamics of two metric...
We consider, from several complementary perspectives, the physics of confinement and deconfinement in the 2+1 dimensional Georgi-Glashow model. Polyakov's monopole plasma and 't Hooft's vortex...
Multi(Scale)Gravity: A Telescope for the Micro-World (2001)
This is a talk presented at XXXVIth Rencontres de Moriond, ElectroWeak Interactions and Unified Theories, March 2001. A short review of modern status of multigravity, i.e. modification of gravity at...
Multi-Localization in Multi-Brane Worlds (2001)
Kogan, Ian I., Mouslopoulos, Stavros, Papazoglou, Antonios, Ross, Graham G.
We study bulk fields in various multi-brane models with localized gravity. In the case of spin 0, 1/2 and 3/2 fields, the non-trivial background geometry itself can induce (multi-) localization of...
H-Branes and Chiral Strings (2001)
Kogan, Ian I., Reis, Nuno B. B.
We add a simple boundary term to the Polyakov action and construct a new class of D-branes with a single null direction. On the string world-sheet the system is described by a single quantized...
Multigravity in six dimensions: Generating bounces with flat positive tension branes (2001)
Kogan, Ian I., Mouslopoulos, Stavros, Papazoglou, Antonios, Ross, Graham G.
We present a generalization of the five dimensional multigravity models to six dimensions. The key characteristic of these constructions is that that we obtain solutions which do not have any...
Radion in Multibrane World (2001)
Kogan, Ian I., Mouslopoulos, Stavros, Papazoglou, Antonios, Pilo, Luigi
The radion dynamics related to the presence of moving branes with both positive or negative tensions is studied in the linearized approximation. The radion effective Lagrangian is computed for a...
Deconfinement at N>2: SU(N) Georgi-Glashow model in 2+1 dimensions (2001)
Kogan, Ian. I, Kovner, Alex, Tekin, Bayram
We analyse the deconfining phase transition in the SU(N) Georgi-Glashow model in 2+1 dimensions. We show that the phase transition is second order for any N, and the universality class is different...
Hagedorn transition, vortices and D0 branes: Lessons from 2+1 confining strings (2001)
Kogan, Ian. I, Kovner, Alex, Schvellinger, Martin
We study the behaviour of Polyakov confining string in the Georgi-Glashow model in three dimensions near confining-deconfining phase transition described in hep-th/0010201. In the string language,...
Numerical analysis of the Minimal and Two-Liquid models of the Market Microstructure (2001)
Chan, David L. C., Eliezer, David, Kogan, Ian I.
We present results of numerical analysis of several simple models for the microstructure of a double auction market without intermediaries which were introduced in cond-matt/9808240. We perform...
Instanton molecules at high temperature - the Georgi-Glashow model and beyond (2001)
Kogan, Ian I., Kovner, Alex, Tekin, Bayram
We show that correlators of some local operators in gauge theories are sensitive to the presence of the instantons even at high temperature where the latter are bound into instanton-anti-instanton...
The chicken or the egg; or Who ordered the chiral phase transition? (2001)
Kogan, Ian I., Kovner, Alex, Tekin, Bayram
We draw an analogy between the deconfining transition in the 2+1 dimensional Georgi-Glashow model and the chiral phase transition in 3+1 dimensional QCD. Based on the detailed analysis of the former...
Hagedorn inflation of D-branes (2001)
Abel, Steven A., Freese, Katherine, Kogan, Ian I.
We examine the cosmological effects of the Hagedorn phase in models where the observable universe is pictured as a D-brane. It is shown that, even in the absence of a cosmological constant, winding...
Open and Unoriented Strings from Topological Membrane - I. Prolegomena (2000)
Ferreira, P. Castelo, Kogan, Ian I.
We study open and unoriented strings in a Topological Membrane (TM) theory through orbifolds of the bulk 3D space. This is achieved by gauging discrete symmetries of the theory. Open and unoriented...
World Sheet Logarithmic CFT in AdS Strings, Ghost-Matter Mixing and M-theory (2000)
Kogan, Ian I., Polyakov, Dimitri
We discuss several closely related concepts in the NSR formulation of superstring theory. We demonstrated that recently proposed NSR model for superstrings on $AdS_5 \times S^5$ is described by the...
Kogan, Ian I., Mouslopoulos, Stavros, Papazoglou, Antonios
We show that, by considering physics in dS_4 or AdS_4 spacetime, one can circumvent the van Dam - Veltman - Zakharov theorem which requires that the extra polarization states of a massive graviton do...
A new bigravity model with exclusively positive branes (2000)
Kogan, Ian I., Mouslopoulos, Stavros, Papazoglou, Antonios
We propose a new ``bigravity'' model with two positive tension AdS_4 branes in AdS_5 bulk and no negative tension branes. The bounce of the ``warp'' factor mimics the effect of a negative brane and...
Deconfining Phase Transition in 2+1 D: the Georgi-Glashow Model (2000)
Dunne, Gerald, Kogan, Ian I., Kovner, Alex, Tekin, Bayram
We analyze the finite temperature deconfining phase transition in 2+1 dimensional Georgi-Glashow model. We show explicitly that the transition is due to the restoration of the magnetic $Z_2$ symmetry...
Topological Effects in Our Brane World From Extra Dimensions (2000)
Dvali, G., Kogan, Ian I., Shifman, M.
The theories in which our world presents a domain wall (brane) embedded in large extra dimensions predict new types of topological defects. These defects arise due to the fact that the brane on which...
Multi-Brane Worlds and modification of gravity at large scales (2000)
Kogan, Ian I., Mouslopoulos, Stavros, Papazoglou, Antonios, Ross, Graham G.
We discuss the implications of multi-brane constructions involving combinations of positive and negative tension brane and show how anomalously light KK states emerge when negative tension ''-''...
Hagedorn inflation of D-branes (2000)
Abel, Steven, Freese, Katherine, Kogan, Ian I.
We examine the cosmological effects of the Hagedorn phase in models where the observable universe is pictured as a D-brane. It is shown that, even in the absence of a cosmological constant, winding...
Holographic renormalization group flow, Wilson loops and field-theory beta-functions (2000)
Kogan, Ian I., Schvellinger, Martin, Tekin, Bayram
We study the Renormalization Group (RG) flow of critical bosonic background fields in the framework of the RG approach to string theory. In this approach quantum field theory beta-functions are the...
Toroidal Compactification in String Theory from Chern-Simons Theory (2000)
Ferreira, P. Castelo, Kogan, Ian I., Tekin, Bayram
A detailed study of the charge spectrum of three dimensional Abelian Topological Massive Gauge Theory (TMGT) is given. When this theory is defined on a manifold with two disconnected boundaries there...
Boundary Logarithmic Conformal Field Theory (2000)
Kogan, Ian I., Wheater, John F.
We discuss the effect of boundaries in boundary logarithmic conformal field theory and show, with reference to both $c=-2$ and $c=0$ models, how they produce new features even in bulk correlation...
Brane Universe and Multigravity: Modification of gravity at large and small distances (2000)
Kogan, Ian I., Ross, Graham G.
We consider a modification of gravity at large distances in a Brane Universe which was discussed recently. In these models the modification of gravity at large distances is ultimately connected to...
Logarithmic Operators in the Theory of Plateau Transition (1999)
Kogan, Ian I., Tsvelik, Alexei M.
We show that $SL(2;C)/SU(2)$ model which had been recently proposed to describe the behaviour of the local densities of states at the plateau transition in Integer Quantum Hall effect, has...
Gauge Invariant Variational Approach with Fermions: the Schwinger Model (1999)
Brown, William E., Garrahan, Juan P., Kogan, Ian I., Kovner, Alex
We extend the gauge invariant variational approach of Phys. Rev. D52 (1995) 3719, hep-th/9408081, to theories with fermions. As the simplest example we consider the massless Schwinger model in 1+1...
What does E_8 know about 11 dimensions ? (1999)
Kogan, Ian I., Wheater, John F.
We discuss some possible relationships in gauge theories, string theory and M theory in the light of some recent results obtained in gauge invariant supersymmetric quantum mechanics. In particular...
Singletons and Logarithmic CFT in ADS/CFT correspondence (1999)
We discuss a possible relation between singletons in $AdS$ space and logarithmic conformal field theories at the boundary of $AdS$. It is shown that the bulk Lagrangian for singleton field (singleton...
Scale Invariance of Dirac Condition $g_e g_m = 1$ in Type 0 String Approach to Gauge Theory (1999)
In this letter we shall discuss a description of non-supersymmetric four-dimensional Yang-Mills theory based on Type 0 strings recently proposed by Klebanov and Tseytlin. The three brane near-horizon...
Scaling Laws for the Market Microstructure of the Interdealer Broker Markets (1998)
We propose a series of simple models for the microstructure of a double auction market without intermediaries. We specialize to those markets, such interdealer broker markets, which are dominated by...
Instantons and the QCD Vacuum Wavefunctional (1998)
Brown, William E., Garrahan, Juan P., Kogan, Ian I., Kovner, Alex
We analyze the instanton transitions in the framework of the gauge invariant variational calculation in the pure Yang-Mills theory. Instantons are identified with the saddle points in the integration...
Gravitationally dresed RG flows and zig-zag invariant strings (1998)
Kogan, Ian. I., Soloviev, O. A.
We propose a world-sheet realization of the zigzag-invariant bosonic and fermionic strings as a perturbed Wess-Zumino-Novikov-Witten model at large negative level $k$ on a group manifold $G$ coupled...
Kogan, Ian I., Kovner, Alex, Shifman, M. A.
An alternative pattern of the chiral symmetry breaking, suggested recently by Stern, is investigated. It could be self-consistent provided that the chiral $SU(N_f) \times SU(N_f)$ symmetry is broken...
D-Instantons on the boundary (1998)
The Maldacena's proposal has established an intriguing connection between string theory in AdS spaces and gauge theory. In this paper we study the effects of adding D(-1)-branes to the system of D3-...
Black Hole Spectrum, Horison Quantization and All That: (2 + 1)-Dimensional Example . (1998)
Black Hole Spectrum, Horison Quantization, All That, Ian I. Kogan
We discuss the possibility that quantum black holes have discrete mass spectrum. Different arguments leading to this conclusion are considered, particularly the decoupling between left and right...
On Gravitational Dressing of 2D Field Theories in Chiral Gauge (1998)
After giving a pedagogical review of the chiral gauge approach to 2D gravity, with particular emphasis on the derivation of the gravitational Ward identities, we discuss in some detail the...
Two Phases of Supersymmetric Gluodynamics (1998)
We argue that supersymmetric gluodynamics has two phases with equivalent infrared behavior, one of which is asymptotically free and another one is superstrongly coupled in the ultraviolet domain....
Matching Conditions and Duality in (1998)
Ian I. Kogan, Mikhail Shifman, Arkady Vainshtein
We discuss duality in N = 1 SUSY gauge theories in Seiberg's conformal window, (3N c =2) ! N f ! 3N c . It is shown that the standard 't Hooft matching conditions -- the basic tool for establishing...
A new relation between two-dimensional conformal field theories and three-dimensional topologically massive gauge theories is found, where the dynamical nature of the 3d theory is ultimately...
More on Supersymmetric Domain Walls, N Counting and Glued Potentials (1997)
Kogan, Ian I., Kovner, Alex, Shifman, Mikhail
Various features of domain walls in supersymmetric gluodynamics are discussed. We give a simple field-theoretic interpretation of the phenomenon of strings ending on the walls recently conjectured by...
Cos(M)ological Solutions in M- and String Theory (1997)
Kaloper, Nemanja, Kogan, Ian I., Olive, Keith A.
We consider solutions to the cosmological equations of motion in 11 dimensions with and without 4-form charges. We show explicitly the correspondence between some of these solutions and known...
Origin of Logarithmic Operators in Conformal Field Theories (1997)
We study logarithmic operators in Coulomb gas models, and show that they occur when the ``puncture'' operator of the Liouville theory is included in the model. We also consider WZNW models for...
A variational approach to the QCD wavefunctional: Calculation of the QCD beta-function (1997)
Brown, William E., Kogan, Ian I.
The beta-function is calculated for an SU(N) Yang-Mills theory from an ansatz for the vacuum wavefunctional. Direct comparison is made with the results of calculations of the beta-function of QCD. In...
Quantum Phenomenology for the Disoriented Chiral Condensate (1997)
We consider the quantum state describing the Disoriented Chiral Condensate (DCC), which may be produced in high energy collisions. We show how a mean field treatment of the quantum equations...
Matrix Strings in Two-dimensional Yang-Mills Theory (1997)
Kogan, Ian I., Szabo, Richard J.
We describe the structure of string vacuum states in the supersymmetric matrix model for M theory compactified on a circle in the large-N limit. We show that the theory admits topological instanton...
Kogan, Ian I., Wheater, John F.
We consider new objects in bosonic open string theory -- ND tadpoles, which have N(euman) boundary conditions at one end of the world-sheet and D(irichlet) at the other, must exist due to s-t duality...
Compact QED3 with theta term and axionic confining strings (1997)
Brown, William E., Kogan, Ian I.
We discuss three dimensional compact QED with a theta term due to an axionic field. The variational gauge invariant functional is considered and it is shown that the ground state energy is...
Liouville Dressed Weights and Renormalization of Spin in Topologically Massive Gravity (1997)
Kogan, Ian I., Szabo, Richard J.
We examine the relations between observables in two- and three-dimensional quantum gravity by studying the coupling of topologically massive gravity to matter fields in non-trivial representations of...
Dynamical Description of Spectral Flow in N=2 Superconformal Field Theories (1997)
Cooper, Leith, Kogan, Ian I., Szabo, Richard J.
We show how the spectral flow between the Neveu-Schwarz and Ramond sectors of N=2 superconformal field theories can be described in three dimensions in terms of the propagation of charged particles...
String Winding Modes From Charge Non-Conservation in Compact Chern-Simons Theory (1996)
Cooper, Leith, Kogan, Ian I., Lee, Kai-Ming
In this letter we show how string winding modes can be constructed using topological membranes. We use the fact that monopole-instantons in compact topologically massive gauge theory lead to charge...
Three-dimensional description of the $\Phi_{1,3}$ deformation of minimal models (1996)
We discuss the $2+1$ dimensional description of the $\Phi_{1,3}$ deformation of the minimal model $M_p$ leading to a transition $M_p \rightarrow M_{p-1}$. The deformation can be considered as an...
Gauge Dressing of 2D Field Theories (1996)
Kogan, Ian I., Lewis, Alex, Soloviev, Oleg A.
By using the gauge Ward identities, we study correlation functions of gauged WZNW models. We show that the gauge dressing of the correlation functions can be taken into account as a solution of the...
D-Brane Recoil and Logarithmic Operators (1996)
Kogan, Ian I., Mavromatos, Nick E., Wheater, John F.
We construct the pair of logarithmic operators associated with the recoil of a $D$-brane. This construction establishes a connection between a translation in time and a world-sheet rescaling. The...
The Liouville Theory as a Model for Prelocalized States in Disordered Conductors (1996)
Kogan, Ian. I., Mudry, C., Tsvelik, A. M.
It is established that the distribution of the zero energy eigenfunctions of (2 + 1)-dimensional Dirac electrons in a random gauge potential is described by the Liouville model. This model has a line...
Boundary Conditions and Heterotic Construction in Topological Membrane Theory (1996)
Using the topological membrane approach to string theory, we suggest a geometric origin for the heterotic string. We show how different membrane boundary conditions lead to different string theories....
World-Sheet Logarithmic Operators and Target Space Symmetries in String Theory (1995)
Kogan, Ian I., Mavromatos, Nick E.
We discuss the target-space interpretation of the world-sheet logarithmic operators in string theory. These operators generate the normalizable zero modes (discrete states) in target space, which...
Logarithmic Operators and Hidden Continuous Symmetry in Critical Disordered Models (1995)
We study the model of (2 + 1)-dimensional relativistic fermions in a random non-Abelian gauge potential at criticality. The exact solution shows that the operator expansion contains a conserved...
Two dimensional QCD with matter in adjoint representation: What does it teach us? (1995)
Kogan, Ian I., Zhitnitsky, Ariel R.
We analyse the highly excited states in $QCD_2 (N_{c}\rightarrow\infty) $ with adjoint matter by using such general methods as dispersion relations, duality and unitarity. We find the Hagedorn-like...
Matching Conditions and Duality in N=1 SUSY Gauge Theories in the Conformal Window (1995)
Kogan, Ian I., Shifman, Mikhail, Vainshtein, Arkady
We discuss duality in $N=1$ SUSY gauge theories in Seiberg's conformal window, $(3N_c/2)
The Two Phases of Topologically Massive Compact $U(1)$ Theory (1995)
The mean field like gauge invariant variational method formulated recently, is applied to a topologically massive QED in 3 dimensions. We find that the theory has a phase transition in the Chern...
Topologically Massive Gauge Theory with O(2) Symmetry (1995)
We discuss the structure of the vacua in $O(2)$ topologically massive gauge theory on a torus. Since $O(2)$ has two connected components, there are four classical vacua. The different vacua impose...
Two Phases of Supersymmetric Gluodynamics (1995)
Kogan, Ian I., Shifman, Mikhail
We argue that supersymmetric gluodynamics has two phases with equivalent infrared behavior, one of which is asymptotically free and another one is superstrongly coupled in the ultraviolet domain.
ON GRAVITATIONAL DRESSING OF 2D FIELD THEORIES IN CHIRAL GAUGE (1995)
After giving a pedagogical review of the chiral gauge approach to 2D gravity, with particular emphasis on the derivation of the gravitational Ward identities, we discuss in some detail the...
Black Hole Spectrum, Horison Quantization and All That (1994)
We discuss the possibility that quantum black holes have discrete mass spectrum. Different arguments leading to this conclusion are considered, particularly the decoupling between left and right...
Compact QED$_3$ - a simple example of a variational calculation in a gauge theory (1994)
We apply a simple mean field like variational calculation to compact QED in 2+1 dimensions. Our variational ansatz explicitly preserves compact gauge invariance of the theory. We reproduce in this...
A variational approach to the QCD wave functional:Dynamical mass generation and confinement (1994)
We perform a variational calculation in the SU(N) Yang Mills theory in 3+1 dimensions. Our trial variational states are explicitly gauge invariant, and reduce to simple Gaussian states in the zero...
Gravitationally Dressed Conformal Field Theory and Emergence of Logarithmic Operators (1994)
We study correlation functions in two-dimensional conformal field theory coupled to induced gravity in the light-cone gauge. Focussing on the fermion four-point function, we display an unexpected...
Quantum Phenomenology for the Disoriented Chiral Condensate (1994)
We consider the quantum state describing theDisoriented Chiral Condensate (DCC), which may be produced in high energy collisions. We show how a mean field treatment of the quantum equations...
We discuss a quantum \qa symmetry in Landau problem, which naturally arises due to the relation between the \qa and the group of magnetic translations. The last one is connected with the \w and...
The Goldberger -- Treiman Relation, $g_A$ and $g_{\pi NN}$ at $T\neq 0$ (1993)
The Goldberger-Treiman relation is shown to persist in the chiral limit at finite temperatures to order $O(T^2)$. The $T$ dependence of $g_A$ turns out to be the same as for $F_{\pi}$,...
Hot Gauge Theories and $Z_{N}$ Phases (1993)
In this paper the several aspects of the $Z_{N}$ symmetry in gauge theories at high temperatures are discussed. The metastable $Z_{N}$ bubbles in the $SU(N)$ gauge theories with fermions may have,...
Squeezed Quantum State of Disoriented Chiral Condensate (1993)
We consider the quantum state describing the Disoriented Chiral Condensate (DCC) which may be produced in high energy collisions. Using the approach suggested by Rajagopal and Wilczek to describe the...
Axions, Monopoles and Cosmic String (1993)
We are discussing some aspects of the magnetic monopoles and cosmic strings interactions with axion domain walss and membranes. The monopole moving through an axion domain wall is transformed into a...
Two Dimensional Field Theory Description of Disoriented Chiral Condensate (1993)
We consider the effective $1+1$-dimensional chiral theory describing fluctuations of the order parameter of the Disoriented Chiral Condensate (DCC) which can be formed in the central rapidity region...
The Spectrum of Topologically Massive Quantum Electrodynamics (1993)
Dobroliubov, Mikhail I., Eliezer, David, Kogan, Ian I., Semenoff, Gordon W., Szabo, Richard J.
We discuss the possibility for the spectrum of topologically massive quantum electrodynamics with spinor matter fields to contain unexpected and unusual stable particle excitations for certain values...
Area Preserving Diffeomorphisms and $W_{\infty}$ Symmetry in a $2+1$ Chern-Simons Theory (1992)
We discuss the $W_{\infty}$ symmetry in the $2+1$ gauge theory with the Chern-Simons term. It is shown that the generators of this symmetry act on the ground state as the canonical transformations in...
Induced QCD and Hidden Local ZN Symmetry (1992)
Kogan, Ian I, Semenoff, Gordon W, Weiss, Nathan
We show that a lattice model for induced lattice QCD which was recently proposed by Kazakov and Migdal has a $Z_N$ gauge symmetry which, in the strong coupling phase, results in a local confinement...
About some exact solutions for 2+1 gravity coupled to gauge fields (1992)
Some exact static solutions for Einstein gravity in 2+1 dimensions coupled to abelian gauge field are discussed. Some of these solutions are three-dimensional analogs of the Schwarzschild black...