Tue, 02 Nov 2010
17:00 -
18:00
L2
Mon, 22 Feb 2010
12:00 -
13:00
L3
Generalized scaling and integrability from AdS5 x S5
Riccardo Ricci
(Imperial College)
Abstract
According to AdS/CFT a remarkable correspondence exists between strings in AdS5 x S5 and operators in N=4 SYM. A particularly important case is that of fast-spinning folded closed strings and the so called twist-operators in the gauge theory. This is a remarkable tool for uncovering and checking the detailed structure of the AdS/CFT correspondence and its integrability properties. In this talk I will show how to match the expression of the anomalous dimension of twist operators as computed from the quantum superstring with the result obtained from the Bethe ansatz of SYM. This agreement resolves a long-standing disagreement between gauge and string sides of the AdS/CFT duality and provides a highly nontrivial strong coupling test of SYM integrability.
Mon, 15 Feb 2010
12:00 -
13:00
L3
N=2 Superconformal Theories and M5 branes
Sergio Benvenuti
(Imperial College)
Abstract
In 2009 there was progress in understanding and classifying the set of four dimensional field theories with N=2 SUSY. These models arise as M5 branes wrapped over a Riemann surface. We review this construction and describe a five dimensional point of view, using (p,q)-webs of 5-branes in Type IIB string theory. This point of view makes many properties of the theories explicit. We will also touch on the AGT correspondence, that associates a 2-dimensional CFT, similar to the Liouville CFT, to the protected sector of four dimensional N=2 models.
Mon, 08 Feb 2010
12:00 -
13:00
L3
Holographic Superconductors in M-Theory
Jerome Gauntlett
(Imperial College)
Abstract
By constructing black hole solutions of D=11 supergravity we analyse the phase diagram of a certain class of three dimensional conformal field theories at finite temperature and finite charge density. The system exhibits superconductivity at lotemperatures and furthermore at zero tmeperature and finite charge density the system exhibits an emergent quantum critical behaviour with conformal symmetry. The construction of the black hole solutions rely on a new understanding of Kaluza-Klein reductions on seven dimensional Sasaki-Einstein manifolds.
Mon, 09 Nov 2009
12:00 -
13:00
L3
On the classification of Brane Tilings
Amihay Hanany
(Imperial College)
Abstract
Brane Tilings give a large class of SCFT's in 3+1 and 2+1 dimensions. In this talk I will discuss several attempt to classify all such models. Statistical properties of these models can be derived using some techniques in number theory.
Mon, 18 May 2009
12:00 -
13:00
L3
Dynamical Logic
Fay Dowker
(Imperial College)
Abstract
Abstract: Despite the high regard in which physicists hold General Relativity, the spacetime nature of reality has not yet fully been taken to heart in addressing the question of the interpretation of quantum mechanics. Partial progress was made by Dirac and Feynman by casting the dynamical content of quantum theory in terms of a Sum Over (spacetime) Histories (SOH). Recently it has been suggested by Sorkin that this SOH is part of an interpretive framework in which the rules of inference that are used to reason about physical reality are themselves subject to dynamical law. Just as General Relativity showed that geometry is not fixed and absolute, so Quantum Mechanics may be telling us that logical rules of inference are not fixed but part of physics.
Tue, 25 Nov 2008
17:00 -
18:00
L2
On the abstract images of profinite groups
Nikolay Nikolov
(Imperial College)
Abstract
I will discuss the following
Conjecture B: Finitely generated abstract images of profinite groups are finite.
I will explain how it relates to the width of words and conjugacy classes in finite groups. I will indicate a proof in the special case of 'non-universal' profinite groups and propose several directions for future work.
This conjecture arose in my discussions with various participants of a workshop in Blaubeuren in May 2007 for which I am grateful. (You know who you are!)
Thu, 06 Nov 2008
12:30 -
13:30
Gibson 1st Floor SR
On the existence of extreme waves and the Stokes conjecture with vorticity
Eugen Varvaruca
(Imperial College)
Abstract
We present some recent results on singular solutions of the problem of travelling gravity water waves on flows with vorticity. We show that, for a certain class of vorticity functions, a sequence of regular waves converges to an extreme wave with stagnation points at its crests. We also show that, for any vorticity function, the profile of an extreme wave must have either a symmetric corner of 120 degrees or a horizontal tangent at any isolated stagnation point. Moreover, the profile necessarily has a symmetric corner of 120 degrees if the vorticity is nonnegative near the free surface.
Mon, 09 Jun 2008
12:00 -
13:00
L3
`Exceptional' generalised geometry and superpotentials
Dan Waldram
(Imperial College)
Abstract
Abstract: We discuss an extension of Hitchin's generalised geometry, based on the
exceptional groups, that provides a unified geometrical description of
supersymmetric flux backgrounds in eleven-dimensional supergravity. We focus
on N=1 seven-dimensional compactifications. The background is characterised
by an element phi, the analogue of the generalised complex structure, that
lies in a particular orbit of the 912 representation of E7. As an
application we show that the four-dimensional effective superpotential takes
a universal form, that is, a homogeneous E7-invariant functional of phi.
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