Forthcoming events in this series


Wed, 06 Jun 2007
12:00
L3

Constructing Gauge Theory Amplitudes

Ruth Britto
(Amsterdam)
Abstract
 
Gauge theory amplitudes lie at the meeting ground of perturbative QCD and twistor string theory.  The past three years have seen dramatic developments in the analytic computation of amplitudes and their interpretation in twistor space geometry.  I will discuss applications to collider experiments and describe direct, systematic procedures for deriving one-loop amplitudes from tree amplitudes, using new insights regarding unitarity.

 
 
Mon, 04 Jun 2007
12:00
L3

Evaluating gauge-theoretic amplitudes with twistor diagrams

Andrew Hodges
(Oxford)
Abstract
 
Amplitudes in gauge theory at tree-level can be expressed economically in terms of twistor diagrams  (hep-th/0503060, hep-th/0512336). This formalism has recently been used to write down the 8-field scattering amplitudes in a simple form, going beyond the results previously obtained (hep-th/0603101). This talk will give an elementary account of how this is done.
 
Mon, 14 May 2007
12:00
L3

Self-dual supergravity and twistor theory

Martin Wolf
(Imperial College, London)
Abstract
 
By generalizing and extending some of the earlier results derived by Manin and by Merkulov, a twistor description is given of four-dimensional N-extended (gauged) self-dual supergravity with and without cosmological constant. In particular, superconformal structures are introduced and used as a starting point to define complex quaternionic, quaternionic Kaehler and hyper-Kaehler supermanifolds. A supersymmetry generalization of the Penrose and Ward constructions are presented.
 
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

\\common\dfs\htdocs\www\maintainers\reception\enb\abstracts\string-theory\mt06\minasian.shtml

Mon, 13 Nov 2006
12:00
L3

Heterotic Twistor Strings

David Skinner
(Oxford)
Abstract

\\Common\dfs\htdocs\www\maintainers\reception\enb\abstracts\string-theory\mt06\skinner.shtml

Mon, 06 Nov 2006
12:00
L3

Quantizing BPS Black Holes in 4 Dimensions

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

\\Common\dfs\htdocs\www\maintainers\reception\enb\abstracts\string-theory\mt06\pioline.shtml

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.

 /notices/events/abstracts/string-theory/mt06/sparks.shtml