Triangle Seminars

Abstract:
Abstract :
Feynman Graph counting in Quantum Field Theory (QFT) can be formulated in terms
of symmetric groups. This leads to expressions for
graph counting and symmetry factors in terms of topological transition
amplitudes for strings with a cylinder target, related to two dimensional
topological field theory. The details of the interactions in the QFT
are encoded in the boundary conditions which specify
how the strings wind around circles. The QFTs discussed include scalar field theories and QED, where there is no large gauge group.

Abstract:
I will discuss scattering amplitudes in N=2,4,8 SYM in three-dimensions, concentrating on the N=8 case, with an emphasis on which properties of the
N=4, D=4 SYM amplitudes survive under dimensional reduction. The on-shell
supersymmetry algebra makes the SO(N) symmetry of the amplitudes manifest,
while the Lagrangian displays only manifest SO(N-1) symmetry. I will also discuss
the possibility of non-local Yangian-type symmetry, connections to BLG,
and some perspectives on loop level results. Based on 1103.0786 / 1109.2792.

Abstract:
Dimer models are typically studied in condesed matter
physics and combinatorics. The correspondence between
dimer models, toric Calabi-Yaus and quiver gauge theories
on D-branes has had a profound impact in areas ranging
from string phenomenology to mathematics. Today I will discuss
a recently discovered correspondence between dimer models
and integrable systems.