This series consists of talks in the area of Superstring Theory.
I will review BPS line defects in 4d N=2 field theories and describe a technique for calculating their spectra using quiver quantum mechanics.
In this presentation, evidence is given that supersymmetrical theories may be exceptional in their ability to conserve information about space-time representations under the impact of dimensional compactification. This is the essence of the concept of ``SUSY Holography.''
The physics of black hole horizons is intimately connected to the physics of quantum liquids. In this talk I will review the connection and draw lessons about quantum turbulence from black hole dynamics and vice versa. For example, gravitational dynamics reveal that quantum turbulence can behave very differently from normal fluid turbulence in 2d, with long-wavelength excitations rapidly dissolving into small fluctuations and dissipating as in a 3d normal liquid.
After giving a brief overview of holographic entanglement entropy formulas, I will explore a curious feature they imply: when the bulk spacetime includes a black hole, the entanglement entropies often appear to depend on the spacetime geometry inside the horizon. I will ask whether this implies any loss of causality in the field theory. To answer this question, I will present a new general-relativity theorem concerning the causal structure of asymptotically AdS spacetimes, which implies an interesting relationship between bulk and boundary causal domains.
Motivated by the cluster structure of two-loop scattering amplitudes in N = 4 Yang-Mills theory we define cluster polylogarithm functions. We find that all such functions of weight 4 are made up of a single simple building block associated to the A2 cluster algebra. Adding the requirement of locality on generalized Stasheff polytopes, we find that these A2 building blocks arrange themselves to form a unique function associated to the A3 cluster algebra.
I will describe progress in deriving 3d gravity directly from 2d conformal field theory at large central charge 'c'. In a large class of CFTs, using general arguments like modular invariance, crossing symmetry, and the OPE expansion, the spectrum, the entanglement entropy, and certain partition functions can be computed to leading order in a 1/c expansion.
In arXiv:0908.4052, Nekrasov and Shatashvili pointed out that the N=2 instanton partition function in a special limit of the Omega-deformation parameters is characterized by certain thermodynamic Bethe ansatz (TBA) like equations.In this talk I will present an explicit derivation of this fact as well as generalizations to quiver gauge theories. The TBA equations derived entirely within gauge theory have been proposed to encode the spectrum of a large class of quantum integrable systems. I will conclude with some remarks on this correspondence.
We discuss boundary conditions and domain walls in 4d N=4 SYM, focusing on those preserving 4 supercharges. Along the way we revisit the old problem of the quantum-corrected moduli space of 3d N=2 theories.
TBA
The principal chiral sigma model (PCSM) in 1+1 dimensions is asymptotically free and has as SU(N)-valued field with massive excitations. We have found all the exact form factors and two-point function of the Noether-current operators at large N using the integrable bootstrap program. At finite N, only the first non-trivial form factors are found, which give a good long distance approximation for the two-point function. We show how to use these new exact results to study non-integrable deformations. One example is the PCSM coupled to a Yang-Mills field.