Triangle Seminars

Abstract:
This talk will review perturbative and non-perturbative properties of string theory scattering amplitudes with particular emphasis on the constraints imposed by duality with M-theory on their low energy action.

Abstract:
In this talk I will discuss the localisation of supersymmetric gauge theories on Riemannian three-manifolds with the topology of a three-sphere. The three-manifold is always equipped with an almost contact structure and an associated Reeb vector field. The partition function depends only on this vector field and has an explicit expression in terms of the double sine function. In addition, I will discuss the possibility of generalising this work to five dimensions.

Abstract:
Higher spin gravity theories in Anti-de Sitter space have been conjectured to be holographically dual to conformal field theories with vector-like matter fields: in the simplest version of the duality, these are just free CFT's of N-component massless scalars or fermions. After reviewing these conjectures, I will discuss recent new tests of the duality based on comparing the bulk and boundary partition functions. In particular, I will show that the sum over one loop free energies of the infinite set of massless higher spin gauge fields in AdS_{d+1} is precisely consistent with the form of the O(N^0) term in the partition function of the CFT on S^d and S^1xS^{d-1}.

Abstract:
In this talk I will consider brane configurations that include NS5 branes, orientifold planes and anti-branes. I will argue that the class of field theories that live on
such brane configurations admit Seiberg duality. Interactions between branes and orientifold planes will be given a field theory interpretation. In particular a certain repulsive interaction will lead to a non-trivial Coleman-Weinberg potential and dynamical symmetry breaking. I will also discuss the case of type 0' strings and chiral symmetry breaking of the form SU(Nf)xSU(Nf)–>SU(Nf) in a QCD-like theory.