Past String Theory Seminar | Mathematical Institute

Mon, 29 Oct 2007

11:00 - 12:00

What is Twistor-String Theory

Lionel Mason

(Oxford)

Abstract

Abstract: Twistor-string theory is reformulated as a `half-twisted heterotic' theory with target $CP^3$. This in effect gives a Dolbeault formulation of a theory of holomorphic curves in twistor space and gives a clearer picture of the mathematical structures underlying the theory and how they arise from the original Witten and Berkovits models. It is also explained how space-time physics arises from the model. It intended that the lecture be, to a certain extent, pedagogical.

Wed, 24 Oct 2007

12:00 - 13:00

<strong>(Note unusual day)</strong> Bows and Quivers: Instantons on ALF Spaces

Sergey Cherkis

(Trinity College Dublin)

Abstract

Abstract: Self-dual connections on ALF spaces can be encoded in terms of bow diagrams, which are natural generalizations of quivers. This provides a convenient description of the moduli spaces of these self-dual connections. We make some comments about the associated twistor data. Via the Nahm transform we construct two explicit examples: a single instanton and a single monopole on a Taub-NUT space.

Mon, 22 Oct 2007

12:00 - 13:00

Exploring the Calabi-Yau Landscape Along Toric Roads

Maximilian Kreutzer

(Technical University of Vienna)

Abstract

Abstract: Toric geometry provides powerful and efficient combinatorial tools for the construction and analysis of Calabi-Yau manifolds. After recollections of the hypersurface case I present recent results on new Calabi-Yau 3-folds and their mirrors via conifold transitions, ideas for generalizations to higher codimensions and applications to string theory.

Mon, 15 Oct 2007

12:00 - 13:00

Calabi-Yau Metrics and the Solutions of the Laplacian

Volker Braun

(University of Pennsylvania)

Abstract

Abstract: Following Donaldson's approach we compute the Calabi-Yau metric on quintics, a four-generation quotient, Schoen threefolds and quotients thereof. Using the explicit Calabi-Yau metric, we then compute eigenvalues and eigenmodes of the Laplace operator.

Thu, 11 Oct 2007
16:15

Fisher Room

Renormalize 1/N Expansion for Field Theories in Extra Dimensions

Dimitri Kazakov

(Dubna)

Mon, 08 Oct 2007

12:00 - 13:00

Baryonic Moduli Spaces and Counting Chiral Operators in SCFT's

Amihay Hanany

(Imperial College)

Abstract

Abstract: Supersymmetric gauge theories have a spectrum of chiral operators which are preserved under at least 2 supercharges. These operators are sometimes called BPS operators in the chiral ring. The problem of counting operators in the chiral ring is reasonably simple and reveals information about the moduli space of vacua for the supersymmetric gauge theory. In this talk I will review the counting problem and present exact results on the moduli space of both mesonic and baryonic operators for a large class of gauge theories

Mon, 11 Jun 2007
12:00

No Seminar

Wed, 06 Jun 2007
12:00

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

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.

Wed, 30 May 2007
12:00

String sigma RG flow and Perelman's entropy

Arkady Tseytlin

(Imperial College, London)

Mon, 28 May 2007
12:00

Geometry and Matrix Factorisation for D-Branes

Paul Aspinwall

(Duke University)

Mon, 21 May 2007
12:00

The Poincare Conjecture, geometrization and Ricci flow I

Mark Haskins

Mon, 14 May 2007
12:00

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, 07 May 2007
12:00

Towards reduction of type II theories on SU(3) structure manifolds

Amir Kashani-Poor

(Amsterdam)

Mon, 30 Apr 2007
12:00

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.