Forthcoming events in this series


Mon, 30 Apr 2007
12:00
L3

D-brane superpotentials and RG flows on the quintic

Ilka Brunner
(ETH Zurich)
Abstract
    The behaviour of D2-branes on the quintic under complex structure deformations is analysed by combining Landau-Ginzburg techniques with methods from conformal field theory. It is shown that the boundary renormalisation group flow induced by the bulk deformations is realised as a gradient flow of the effective space time superpotential which is calculated explicitly to all orders in the boundary coupling constant.
Mon, 27 Nov 2006
12:00
L3

Twisted Tori and (new) String Vacua

Ruben Minasian
(Ecole Polytechnique and Imperial)
Abstract

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Mon, 13 Nov 2006
12:00
L3

Heterotic Twistor Strings

David Skinner
(Oxford)
Abstract

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Mon, 06 Nov 2006
12:00
L3

Quantizing BPS Black Holes in 4 Dimensions

Boris Pioline
(Universite Paris VI et VII and ENS)
Abstract

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Mon, 23 Oct 2006
12:00
L3

Einstein Geometry and Conformal Field Theory

James Sparks
(Oxford)
Abstract
I shall describe two recent results in Sasaki-Einstein geometry, which is the odd-dimensional cousin of Kahler-Einstein geometry, and how they are related to four-dimensional superconformal field theory (SCFT) via the AdS/CFT correspondence. The first is a proof that the volumes of such Einstein manifolds are always algebraic numbers, which reflects a similar statement about central charges in SCFTs due to Intriligator and Wecht. The second descibes two simple holomorphic obstructions to the existence of such Einstein metrics. In such obstructed cases the non-existence of the dual superconformal fixed point may be proven by a simle application of the unitarity bound and the “a-theorem”, respectively, and these may be related directly to the geometrical obstructions via AdS/CFT arguments. On the mathematical side, these are new simple obstructions to the existence of Kahler-Einstein metrics on Fano orbifolds.

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Mon, 28 Nov 2005
12:00
L3

Topological membranes

Annamaria Sinkovics
Abstract

It is suggested that topological membranes play a fundamental role

in the recently proposed topological M-theory. We formulate a topological theory

of membranes wrapping associative three-cycles in a seven-dimensional target

space with G_2 holonomy. The topological BRST rules and BRST invariant action

are constructed via the Mathai-Quillen formalism. We construct a set of local

and non-local observables for the topological membrane theory. As the BRST

cohomology of local operators turns out to be isomorphic to the de Rham

cohomology of the G_2 manifold, our observables agree with the spectrum of

d=4, N=1 G_2 compactifications of M-theory.

Mon, 21 Nov 2005
12:00
L3

Generalised geometries and supergravity

Dan Waldram
(Imperial)
Abstract

I aim to give some review of how generalised geometries provide a natural

framework for describing supersymmetric string backgrounds. In particular I

will focus on a rewriting of type II supergravity in terms of generalised

structures. Hitchin functions appear naturally along with generalised

extensions of the Gukov-Vafa-Witten superpotential.