String Seminars

This series consists of talks in the area of Superstring Theory.

Seminar Series Events/Videos

Currently there are no upcoming talks in this series.

 

Wednesday May 06, 2009
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Recently methods of integrability were shown to be useful for solving gauge theories in various dimensions. I will make an introduction into integrability in two dimensions and demonstrate how the integrability works also for some three and four dimensional gauge theories.

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Tuesday Mar 24, 2009
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Holographic superconductors provide tractable models for the onset of superconductivity in strongly coupled theories. They have some features in common with experimentally studied nonconventional superconductors. I will review the physics of holographic superconductors and go on to show that many such models are to be found in the string landscape of AdS_4 vacua.

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Tuesday Mar 17, 2009
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A simple model for chaotic inflation in supergravity is proposed. The model is N = 1 supersymmetric massive U(1)gauge theory via the Stuckelberg superfield and gives rise to D-term inflation with a quadratic term of inflaton in the potential. The Fayet-Iliopoulos field plays a role of the inflaton. It is also discussed to give rise to successful reheating and leptogenesis through the inflaton decay.

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Thursday Mar 05, 2009
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The Rozansky-Witten model is a topological sigma-model in three dimensions whose target is a hyper-Kahler manifold. Upon compactification to 2d it reduces to the B-model with the same target. Boundary conditions for the Rozansky-Witten model can be regarded as a 3d generalization of B-branes. While branes form a category, boundary conditions in a 3d TFT form a 2-category. I will describe the structure of this 2-category for the Rozansky-Witten model and its connection with a categorification of deformation quantization.

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Tuesday Feb 24, 2009
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Brane Tilings are known to describe the largest known class of SCFT's in 3+1 dimensions. There is a well established formalism to find AdS_5 x SE_5 duals to these SCFT's and to compare results on both sides. This talk extends this formalism to 2+1 dimensional SCFT's, living on the world volume of M2 branes, which are dual to AdS_4 x SE_7 backgrounds of M theory. The SCFT's are quiver gauge theories with 4 supercharges (N=2 in 2+1 dimensions) and Chern Simons (CS) couplings. They admit a moduli space of vacuum configurations which is a CY4 cone over SE_7.

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Tuesday Feb 10, 2009
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Motivated by recent mathematical developements in non-commutative Donaldson-Thomas theory, we construct a new statistical mechanicalmodel of crystal melting to count BPS bound states of D0 and D2 branes on a single D6 brane wrapping an arbitrary toric Calabi-Yau threefold. We also discuss the wall crossing phenomena, which are crucial for the proper understanding of the relation between the crystal melting and the topological string theory.

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Tuesday Jan 27, 2009
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We derive a universal upper bound on the weight of the lowest primary operator in any two-dimensional conformal field theory with a given central charge. Translated into gravitational language using the AdS/CFT dictionary, our result proves rigorously that the lightest massive state in any theory of 3D gravity and matter with negative cosmological constant can be no heavier than a particular function the cosmological constant and the Planck scale. For a large AdS space, the lower bound approaches the mass of the lightest BTZ black hole.

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Tuesday Jan 20, 2009
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In the past couple of years many new developments have been made in the techniques used for computing one-loop gauge theory amplitudes. These developments have mainly involved exploiting generalized unitarity techniques to construct the coefficients of the basis integral functions which make up a one-loop amplitude. I will outline these new developments along with their application to both QCD and N=8 supergravity amplitudes.

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Thursday Dec 04, 2008

In this talk I discuss methods to determine hydrodynamical dispersion relations from an extra-dimensional gravity dual wherein the metric is supported by scalar fields. Such a setup may eventually be used as a model of the strongly coupled plasma created in heavy ion collisions. I examine examples of both the shear and sound modes. The shear mode is analyzed using the black hole membrane paradigm; a calculation of the shear viscosity is reviewed, and then the calculation is extended to the next hydrodynamical order. All results agree with those found using the AdS/CFT prescription.

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