Mon, 05 May 2014

12:00 - 13:00
L5

The superconformal index of (2,0) theory with defects

Mathew Bullimore
(Perimeter Institute)
Abstract
String theory predicts the existence of a class of interacting superconformal field theories in six dimensions which arise on the world-volume of coincident M5 branes. There are important non-local operators in these theories corresponding to intersecting M2 and M5 branes. I will explain how to compute the superconformal index in the presence of such operators using five-dimensional supersymmetric gauge theory. The answers are in 1-1 correspondence with characters of representations of a class of `chiral algebras’. I will discuss potential applications of this result for bootstrapping correlation functions.
Fri, 23 Nov 2012

12:00 - 13:00
Gibson 1st Floor SR

$\chi$-Systems for Correlation Functions

Jonathan Toledo
(Perimeter Institute)
Abstract
We consider the strong coupling limit of 4-point functions of heavy operators in N=4 SYM dual to strings with no spin in AdS. We restrict our discussion for operators inserted on a line. The string computation factorizes into a state-dependent sphere part and a universal AdS contribution which depends only on the dimensions of the operators and the cross ratios. We use the integrability of the AdS string equations to compute the AdS part for operators of arbitrary conformal dimensions. The solution takes the form of TBA-like integral equations with the minimal AdS string-action computed by a corresponding free-energy-like functional. These TBA-like equations stem from a peculiar system of functional equations which we call a \chi-system. In principle one could use the same method to solve for the AdS contribution in the N-point function. An interesting feature of the solution is that it encodes multiple string configurations corresponding to different classical saddle-points. The discrete data that parameterizes these solutions enters through the analog of the chemical-potentials in the TBA-like equations. Finally, for operators dual to strings spinning in the same equator in S^5 (i.e. BPS operators of the same type) the sphere part is simple to compute. In this case (which is generically neither extremal nor protected) we can construct the complete, strong-coupling 4-point function.
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