Triangle Seminars

Abstract:
I will explain how a novel use of dimer models in string theory sheds light on the non-commutative geometry of toric Calabi-Yau 3-fold singularities (and also explain what this means).

Abstract:
We will discuss how by integrating out a global U(1)B gauge field, the U(n)xU(n) ABJM models at level k are equivalent to SU(n)xSU(n) N=6 Chern-Simons theories with a Zk identification on the fields and a modified flux quantisation condition, but only when n and k are relatively prime. As a consequence, the ABJM model for two M2-branes in R8 can be identified with the N=8 SU(2)xSU(2) theory at k=1. We will also argue that the original N=8 SO(4)-theory of Bagger and Lambert, without modified flux quantisation, is equivalent to the U(2)xU(2) ABJM model at k=2 and hence describes the IR fixed point of a maximally supersymmetric three-dimensional O(4) gauge theory obtained in M-theory by an R8/Z2 orbifold without torsion.

Abstract:
Recently there has been great interest in calculating transport coefficients
for field theories at large coupling, using AdS/CFT. In this talk I will
discuss recent work showing how to use the membrane paradigm to easily
compute the shear viscosity and conductivity in arbitrary gravity theories.
In a certain sense these can be thought of as effective couplings at the
black hole horizon dual to the field theory plasma. An explicit Wald-like
formula for these couplings is given for a large class of generalized
gravity theories.

Abstract:
This is an introduction to Gerbes aimed at physicists. The approach will be to introduce Cech cohmology and its relation to gauge theories, monopoles and Wilson loops and then give the extension to extend these ideas to the relation between higher order Cech cohomolgy, gerbes and strings.

Abstract:
I will present the 1/2 BPS Wilson loop operator of N=6 super Chern-
Simons-matter (ABJM theory) which is dual to the simplest macroscopic
open string in AdS4 x CP3. The Wilson loop couples, in addition to
the gauge and scalar fields of the theory, also to the fermions in the
bi-fundamental representation of the U(N) x U(M) gauge group. These
ingredients are naturally combined into a superconnection whose
holonomy gives the Wilson loop, which can be defined for any
representation of the supergroup U(NlM). Using the localization
calculation of Kapustin et al. I will then show that the circular loop
is computed by a supermatrix model and discuss the connection to pure
Chern-Simons theory with supergroup U(NlM).

Abstract:
In this talk, I will discuss work in progress with Bertrand Eynard, in
which we derive the BKMP remodelling the B-model conjecture, in the
large radius limit. This is the claim that Gromov-Witten invariants of any
toric Calabi-Yau 3-fold coincide with the spectral invariants of the
mirror curve. Our method consists in explicitly constructing a matrix
model which reproduces the topological string partition function obtained
via the vertex formalism, and then demonstrating that the spectral curve
of this matrix model coincides with the mirror geometry.