Forthcoming events in this series


Mon, 14 Jan 2008

11:00 - 12:00
L3

Special Geometry over $\mathbb C$ and $\mathbb Q_p$

Philip Candelas
(Oxford)
Abstract
Abstract: The moduli space of Calabi-Yau manifolds have a natural geometrical structure that has come to be known as special geometry. This geometry will be reviewed in the complex context and it will be shown that much of the structure persists for p-adic Calabi-Yau manifolds.
Mon, 26 Nov 2007

11:00 - 12:00
L3

An algorithmic approach to heterotic compactification

Lara Anderson (Oxford)
Abstract
Abstract: In this talk, I will describe recent work in string phenomenology from the perspective of computational algebraic geometry. I will begin by reviewing some of the long-standing issues in heterotic model building and describe the difficult task of producing realistic particle physics from heterotic string theory. This goal can be approached by creating a large class of heterotic models which can be algorithmically scanned for physical suitability. I will outline a well-defined set of heterotic compactifications over complete intersection Calabi-Yau manifolds using the monad construction of vector bundles. Further, I will describe how a combination of analytic methods and computer algebra can provide efficient techniques for proving stability and calculating particle spectra.
Mon, 19 Nov 2007

11:00 - 12:00
L3

Hedgehog black holes and the deconfinement transition

Matt Headrick
(Stanford University)
Abstract
Abstract: The deconfinement transition in gauge theories, in which the Polyakov loop acquires a non-zero expectation value, is described in AdS/CFT as the formation of a black hole in the dual graviational theory. We will explain how to compute the free energy diagram for the Polyakov loop by a constrained gravitational path integral, leading to a new class of black hole solutions.
Mon, 12 Nov 2007

11:00 - 12:00
L3

AdS/CFT and Geometry

James Sparks
(Oxford)
Abstract
Abstract: I will give an introduction to, and overview of, the AdS/CFT correspondence from a geometric perspective. As I hope to explain, the correspondence leads to some remarkable relationships between string theory, conformal field theory, algebraic geometry, differential geometry and combinatorics.
Mon, 29 Oct 2007

11:00 - 12:00
L3

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
L3

<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
L3

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
L3

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.
Mon, 08 Oct 2007

12:00 - 13:00
L3

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
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

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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.