Aharony
Ofer | TBA | Abstract: TBA |
Ardalan
Farhad | to be announced | Abstract: tba |
Bakas
Ioannis | Algebraic aspects of RG flows and string theory | Abstract: |
Banks
Tom | Asymptotic Darkness and the Structure of Theories of Quantum Gravity | Abstract: |
Baulieu
Laurent | Where does supersymmetry come from? | Abstract: |
Belaloui
Nadir | On the Critical Dimensions for Parastrings | Abstract: We construct the parabosonic and the paraspinning strings formalism based on the paraquantization of both the center of mass variables and the exitation modes of the string. A critical study of the different commutators of the Poincarré algebra is done. Space-time critical dimentions D as functions of the paraquantization orders Q are obtained. |
Belhaj
Adil | On M-theory on G2 manifolds | Abstract: In this talk, we present seven manifolds with G2 holonoly group, as U(1) qoutients of eight hyperKahler manifolds. Then we discuss the physics content of M-theory on such manifolds. |
Bergman
Oren | Branes and quantum Hall dynamics in various dimensions | Abstract: |
D
Giuseppe | String interactions in a gravitational wave background | Abstract: I will discuss three and four-point correlators for a WZW model corresponding to a gravitational wave background and introduced by Nappi and Witten. I will show that this model shares many of the most interesting features of AdS_3 and other non-compact WZW model, providing an ideal setting for a detailed analysis of them, due to its simplicity. Finally I will discuss string amplitudes in this background and comment about its holographic description. |
Dabholkar
Atish | Duality Twists and Moduli Stabilization | Abstract: I will describe the relation between duality twists, fluxes and orbifolds and discuss stabilization of moduli using these techniques. |
David
Justin | Plane waves with weak singularities | Abstract: |
Djordjevic
Goran | NOTES ON NUMBER THEORY IN QUANTUM COSMOLOGY AND TACHYON FIELD THEORY | Abstract: We consider the formulation and some elaboration of p-adic and adelic quantum cosmology. Some discreteness of the minisuperspace and cosmological constant is emphasized. A simplified model of tachyon matter with classical and quantum analogs in classical and quantum mechanics is considered. Path integral quantization of the model is performed. A conjecture that fundamental physics laws should be invariant under interchange of number fields (p-adic and real) is considered and supported. |
Drukker
Nadav | Goedel's universe is not a solution of string theory | Abstract: |
El
Sahraoui | Metric Building of pp Wave Orbifold Geometries | Abstract: We study strings on orbifolds of $AdS_{5}\times S^5$ by SU(2) discrete groups in the Penrose limit. We derive the degenerate metrics of pp wave of $AdS_{5}\times S^5/\Gamma$ using ordinary $ADE$ and affine $\wildtilde{ADE}$ singularities of complex surfaces and results on ${\cal N}=4$ CFT$_4$'s. We also give explicit metric moduli depencies for abelian and non abelian orbifolds. |
Fotopoulos
Angelos | To Be Announced | Abstract: |
Garousi
Mohammad | S-matrix elements and tachyonic effective action | Abstract: We evaluate the disk level S-matrix element of two open string tachyons and two massless scalar vertex operators, and S-matrix element of four tachyons in the presence of background B-flux. By studying these amplitudes in the low energy limit, we find couplings of two scalars with two tachyons, and couplings of four tachyons on the world-volume of the non-BPS D-branes. They are fully consistent with the non-abelian Dirac-Born-Infeld type effective action. They also fix the coefficient of $T^4$ term in the expansion of the tachyon potential around its maximum. This term confirms the Sen conjecture that the tachyon potential has minimum. |
Govindarajan
Suresh | Aspects of Orientifolds of type II strings on Calabi-Yau manifolds | Abstract: Orientifolds of type II strings on Calabi-Yau manifolds furnish examples of four dimensional compactifications with N=1 supersymmetry. We discuss aspects of these orientifolds making contact with recent results on the spectra of D-branes on Calabi-Yau manifolds. |
Hassan
Sayed | N=1 Open String Boundary Couplings and Worldvolume Covariance | Abstract: none |
Hull
Chris | Holonomy and Symmetry in M-theory | Abstract: none |
Imaanpur
Ali | SO(N) N=2 SYM theory from Matrix model | Abstract: Using Matrix model/gauge theory duality proposed by Dijkgraaf and Vafa, it is shown how SO(N) N=2 SYM effective prepotential can be obtained. |
Israel
Dan | Superstrings on NS5 backgrounds, deformed AdS3 and holography | Abstract: I would like to present some new results about string theory on SL(2,R)*SU(2) and related backgrounds, based on a work to appear very soon with C. Kounnas and M. Petropoulos. First, we give a consistent partition function for (super)strings on minkowskian SL(2,R). Then we study the various marginal deformations of SL(2,R), and in particular the null deformation which is shown to correspond to a particular decoupling limit of the NS5/F1 background. We discuss in detail the superconformal structure of the deformed theory and the holographic interpretation. Possibly I would talk about work in progress on related models. |
Kaste
Peter | On the geometry of compactifications with fluxes | Abstract: Background fluxes are one way to reduce supersymmetry in string/M-theory compactifications. Their backreaction implies that the internal metric for the vacuum states are no longer the well studied Ricci-flat metrics of special holonomy. We discuss the constraints on the geometry in terms of G-structures on the internal manifolds. |
Kehagias
Alexandros | Anomaly Free 6D brane worlds | Abstract: I will show how in the N=1 7D supergravity, 6D boundries can consistently introduced. These boundaries contain N=1 6D matter which is restricted by anomaly cancelation. |
Kokorelis
Christos | Chiral compactifications from Intersecting Branes | Abstract: In the context of D6 branes intersecting at angles, we construct non-supersymmetric orbifold models with vanishing NSNS tadpoles. Some phenomenological implications for 3-generation GUTS like SU(5) are discussed. |
Kol
Barak | Black-hole black-string transition and cosmological singularities | Abstract: In the presence of compact dimensions massive solutions of General Relativity may take one of several forms including the black-hole and the black-string, the simplest relevant background being $\IR^{3+1} \times \IS^1$. A minimalistic phase diagram is suggested which describes a first order transition whose only stable phases are the uniform string and the black-hole. The diagram calls for a topology changing ``merger'' transition in which the black-hole evolves continuously into an unstable black-string phase, implying violation of cosmic censorship and black hole uniqueness in 5d. As evidence a local model for the transition is presented in which the cone over S^2 * S^2 plays a central role. A generalization to higher dimensions finds that whereas the cone is unstable for $d=5$, its stability depends interestingly on the dimension - it is unstable for $d<10$, and stable for $d>10$. Surprisingly this is related to recent results on the Belinskii-Lifshitz-Khalatnikov generic approach to a space-like singularity. |
Lopez
Esperanza | Closed string tachyons and noncommutative instabilities | Abstract: We observe a relation between closed strings tachyons and one-loop instabilities in non-supersymmetric non-commutative gauge theories. In particular we analyze the spectra of type IIB string theory on C^3/Z_N orbifold singularities and the non-commutative field theory that lives on D3 branes located at the singularity. We find a surprising correspondence between the existence or not of one-loop low-momentum instabilities in the non-commutative field theory and the existence or not of tachyons in the closed string twisted sectors. Moreover, the relevant piece of the non-commutative field theory effective action is suggestive of an exchange of closed string modes. This suggests that non-commutative field theories retain some information about the dynamics of the underlying string configuration. Finally, we also comment on a possible relation between closed string tachyon condensation and field theory tachyon condensation. |
Minwalla
Shiraz | A Hagedorn Transition in Free Yang Mills | Abstract: We demonstrate that free $SU(N)$ Yang Mills theory on $S^{d-1} \times R$ undergoes a Hagedorn phase transition at infinite $N$. The low temperature phase has a $\CO(1)$ free energy, and is characterized by a stringy exponential growth in its density of states. The high temperature phase displays a field theoretic growth in the density of states; the free energy in this phase is $\propto N^2 f((T)$ where $f(T) \propto T^d$ for $T \gg 1$. The Hagedorn transition between these two phases may be understood as a Gross Witten like phase transition of an auxilliary matrix model. In the case of $N=4, d=4 SYM$ It is natural to conjecture this phase transition is continuously connected to similar transition in strongly coupled gauge theories discussed by Witten in the context of the AdS/ CFT correspondence. This leads to a suggestive connection between the endpoint of the stringy Hagedorn transition and black holes. |
Oz
Yaron | Aspects of N=2 Strings | Abstract: |
Papadopoulos
Georgios | Strings and Waves | Abstract: I shall talk about aspects of string theory in the Penrose limit of AdS and Cosmological backgrounds. |
Parvizi
Shahrokh | Branes in Time-Dependent Orbifolds | Abstract: We study supergravity solutions of Dp-branes in the time-dependent orbifold background. We show that worldvolume theories decouple from the bulk gravity for p less than six. Type II NS5-brane (M5-brane) in the presence of RR n-form for n=0, ..., 4 (C field) in this time-dependent background have also been studied. |
Petropoulos
Marios | Five-brane configurations and the strong-coupling problem | Abstract: |
Polychronakos
Alexios | Entropy, area and ringing modes of black holes | Abstract: Decaying ringing modes of black holes can be used to extract information about their quantum nature. We demonstrate that an equidistant quantization for the area of the black hole in the context of loop quantum gravity can account for both thermodynamic and ringing mode properties of Schwarschild black holes. |
Sadooghi
Neda | TBA | Abstract: |
Saidi
El | On Hyperbolic 4D N=2 Supersymmetric CFTs | Abstract: Using Katz, Klemm and Vafa geometric engineering method of $\QTR{cal}{N}=2$ supersymmetric QFT$_{4}$s and results on the classification of generalized Cartan matrices of Lie algebras, we study the class of $\QTR{cal}{N}=2$ CFT$_{4}$s based on indefinite singularities. It is shown that the vanishing of the general expression of the beta function of $\QTR{cal}{N}=2$ QFT$_{4}$s coincides exactly with the fundamental classification theorem of Kac-Moody Lie algebras. Explicit solutions are derived for mirror geometries of CY threefolds with hyperbolic singularities. |
Sarkar
Subir | Cosmology in wonderland (2 lectures) | Abstract: |
Savvidis
Georgios | Tensionless supersrings and AdS correspondance | Abstract: |
Sonnenschein
Jacob | Supergravity Probing of Mesons of Confining Gauge Theories | Abstract: none |
Tomaras
Theodore | cosmological evolution with brane-bulk energy exchange | Abstract: TBA |
Trivedi
Sandip | Flux Compactifications in String Theory | Abstract: We construct compactifications in string theory where various RR and NS fluxes are excited in the internal directions. These compactifications typically have fewer moduli. We show how related constructions can give rise to dS vacuua and related interesting cosmologies. |
Veneziano
Gabriele | Superstring Cosmology Concepts and Consequences | Abstract: |
West
Peter | Symmetries of M theory | Abstract: |