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Boundary deformation theory and moduli spaces of Dbranes
, 1999
"... Boundary conformal field theory is the suitable framework for a microscopic treatment of Dbranes in arbitrary CFT backgrounds. In this work, we develop boundary deformation theory in order to study the changes of boundary conditions generated by marginal boundary fields. The deformation parameters ..."
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Boundary conformal field theory is the suitable framework for a microscopic treatment of Dbranes in arbitrary CFT backgrounds. In this work, we develop boundary deformation theory in order to study the changes of boundary conditions generated by marginal boundary fields. The deformation parameters may be regarded as continuous moduli of Dbranes. We identify a large class of boundary fields which are shown to be truly marginal, and we derive closed formulas describing the associated deformations to all orders in perturbation theory. This allows us to study the global topology properties of the moduli space rather than local aspects only. As an example, we analyse in detail the moduli space of c = 1 theories, which displays various stringy phenomena.
Monodromy, Duality and Integrability of Two Dimensional String Effective Action
"... hep2001 ..."
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ON THE CONSTRUCTION OF SL(2,Z) TYPE IIB 5BRANES
, 1998
"... This talk reviews our recent work on the construction of SL(2,Z) multiplets of type IIB superfivebranes. We here pay particular attention to the methods employed and some salient features of the solutions. 1 ..."
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This talk reviews our recent work on the construction of SL(2,Z) multiplets of type IIB superfivebranes. We here pay particular attention to the methods employed and some salient features of the solutions. 1
Relativity, “Spacetime 100 Years Later, ” to be published in New Journal of Physics.
, 2004
"... An inexhaustive review of Hawking radiation and black hole thermodynamics is given, focusing especially upon some of the historical aspects as seen from the biased viewpoint of a minor player in the field on and off for the past thirty years. AlbertaThy1804, hepth/0409024, review article solicit ..."
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An inexhaustive review of Hawking radiation and black hole thermodynamics is given, focusing especially upon some of the historical aspects as seen from the biased viewpoint of a minor player in the field on and off for the past thirty years. AlbertaThy1804, hepth/0409024, review article solicited for a celebratory Focus Issue on
HUBEP99/26 DFPD 99/TH/25 hep–th/9906142
, 2002
"... We review the geometrical approach to the description of the dynamics of superparticles, superstrings and, in general, of super–p–branes, Dirichlet branes and the M5brane, which is based on a generalization of the elements of surface theory to the description of the embedding of supersurfaces into ..."
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We review the geometrical approach to the description of the dynamics of superparticles, superstrings and, in general, of super–p–branes, Dirichlet branes and the M5brane, which is based on a generalization of the elements of surface theory to the description of the embedding of supersurfaces into target superspaces. Being manifestly supersymmetric in both, the superworldvolume of the brane and the target superspace, this approach unifies the Neveu–Schwarz–Ramond and the Green–Schwarz formulation and provides the fermionic κ–symmetry of the Green–Schwarz–type superbrane actions with a clear geometrical meaning of standard worldvolume local supersymmetry. The dynamics of superbranes is encoded in a generic superembedding condition. Depending on the superbrane and the target–space dimension, the superembedding condition produces either only off–shell constraints (as in the case of N = 1 superparticles and N = 1 superstrings), or also results in the full set of the superbrane equations of motion (as, for example, in the case of the M–theory branes).
HUBEP99/26 DFPD 99/TH/25
, 1999
"... Reviewed is a geometrical approach to the description of the dynamics of superparticles, superstrings and, in general, of super–p–branes, Dirichlet branes and the M5brane, which is based on a generalization of the elements of surface theory to the description of the embedding of supersurfaces into ..."
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Reviewed is a geometrical approach to the description of the dynamics of superparticles, superstrings and, in general, of super–p–branes, Dirichlet branes and the M5brane, which is based on a generalization of the elements of surface theory to the description of the embedding of supersurfaces into target superspaces. Being manifestly supersymmetric in both, the superworldvolume of the brane and the target superspace, this approach unifies the Neveu–Schwarz–Ramond and the Green–Schwarz formulation and provides the fermionic κ–symmetry of the Green–Schwarz–type superbrane actions with a clear geometrical meaning of standard worldvolume local supersymmetry. The dynamics of superbranes is encoded in a generic superembedding condition. Depending on the superbrane and the target–space dimension, the superembedding condition produces either only off–shell constraints (as in the case of N = 1 superparticles and N = 1 superstrings), or also results in the full set of the superbrane equations of motion (as, for example, in the case of the M–theory branes).
Workshop on Integrable Field Theories, Solitons and Duality. PROCEEDINGS Monodromy, Duality and Integrability of Two Dimensional String Effective Action
, 2002
"... Abstract: In this talk, we show how the monodromy matrix, ̂ M, can be constructed for the two dimensional tree level string effective action. The pole structure of ̂ M is derived using its factorizability property. It is shown that the monodromy matrix transforms nontrivially under the noncompact ..."
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Abstract: In this talk, we show how the monodromy matrix, ̂ M, can be constructed for the two dimensional tree level string effective action. The pole structure of ̂ M is derived using its factorizability property. It is shown that the monodromy matrix transforms nontrivially under the noncompact Tduality group, which leaves the effective action invariant and this can be used to construct the monodromy matrix for more complicated backgrounds starting from simpler ones. We construct, explicitly, ̂ M for the exactly solvable NappiWitten model, both when B = 0 and B ̸ = 0, where these ideas can be directly checked. 1.
2.GNPHE, Groupement National de Physique des Hautes Energies,
, 2008
"... We construct the Generalized Monodromy matrix ˆ M(ω) of two dimensional string effective action by introducing the Tduality group properties.The integrability conditions with general solutions depending on spectral parameter are given. This construction is investigated for the exactly solvable Wess ..."
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We construct the Generalized Monodromy matrix ˆ M(ω) of two dimensional string effective action by introducing the Tduality group properties.The integrability conditions with general solutions depending on spectral parameter are given. This construction is investigated for the exactly solvable Wess, Zumino, Novikov and Witten (WZNW) model in ppwave Limit when B=0. key words: Tduality Symmetries, Two dimensional Non linear sigma models,
Equatorial photon motion in the Kerr–Newman spacetimes with a nonzero cosmological constant‡
, 803
"... Abstract. Discussion of the equatorial photon motion in Kerr–Newman blackhole and nakedsingularity spacetimes with a nonzero cosmological constant is presented. Both repulsive and attractive cosmological constants are considered. An appropriate ‘effective potential ’ governing the photon radial mo ..."
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Abstract. Discussion of the equatorial photon motion in Kerr–Newman blackhole and nakedsingularity spacetimes with a nonzero cosmological constant is presented. Both repulsive and attractive cosmological constants are considered. An appropriate ‘effective potential ’ governing the photon radial motion is defined, circular photon orbits are determined, and their stability with respect to radial perturbations is established. The spacetimes are divided into separated classes according to the properties of the ‘effective potential’. There is a special class of Kerr–Newman–de Sitter blackhole spacetimes with the restricted repulsive barrier. In such spacetimes, photons with high positive and all negative values of their impact parameter can travel freely between the outer blackhole horizon and the cosmological horizon due to an interplay between the rotation of the source and the cosmological repulsion. It is shown that this type of behavior of the photon motion is connected to an unusual relation between the values of the impact parameters of the photons and their directional angles relative to outward radial direction as measured in the locally nonrotating frames. Surprisingly,