Wed, 15 Feb 2012
16:00
L3

tba

Nick Bezhanishvili
(Imperial College)
Mon, 23 May 2011

12:00 - 13:00
L3

Trivertices and SU(2)'s

Amihay Hanany
(Imperial College)
Abstract
Given a graph with lines and 3-valent vertices, one can construct, using a simple dictionary, a Lagrangian that has N=2 supersymmetry in 3+1 dimensions. This is a construction which generalizes the notion of a quiver. The vacuum moduli space of such a theory is well known to give moment map equations for a HyperKahler manifold. We will discuss the class of hyperkahler manifolds which arise due to such a construction and present their special properties. The Hilbert Series of these spaces can be computed and turns out to be a function of the number of external legs and loops in the graph but not on its detailed structure. The corresponding SCFT consequence of this property indicates a crucial universality of many Lagrangians, all of which have the same dynamics. The talk is based on http://arXiv.org/pdf/1012.2119.
Fri, 11 Mar 2011
16:00
L3

"Topos theory in the foundations of physics"

Chris Isham
(Imperial College)
Abstract

I will consider the physical background, and general thinking behind, the recent programme aimed at applying topos theory to the foundations of physics.

Mon, 28 Feb 2011

12:00 - 12:45
L3

The Topology of DNA-Protein Interactions

Karin Valencia
(Imperial College)
Abstract

The central axis of the famous DNA double helix can become knotted
or linked as a result of numerous biochemical processes, most notably
site-specific recombination. Site-specific recombinases are naturally
occurring enzymes that cleave and reseal DNA molecules in very precise ways.
As a by product of their main purpose, they manipulate cellular DNA in
topologically interesting and non-trivial ways. So if the axis of the DNA
double helix is circular, these cut-and-seal mechanisms can be tracked by
corresponding changes in the knot type of the DNA axis.  In this talk, I'll
explain several topological strategies to investigate these biological
situations. As a concrete example, I will disscuss my recent work, which
predics what types of DNA knots and links can arise from site-specific
recombination on DNA twist knots.

Mon, 07 Feb 2011
17:00
Gibson 1st Floor SR

Asymptotic analysis for the Generalized Langevin equation

Grigoris Pavliotis
(Imperial College)
Abstract

In this talk we will present some recent results on the long time

asymptotics of the generalized (non-Markovian) Langevin equation (gLE). In particular,

we will discuss about the ergodic properties of the gLE and present estimates on the rate of convergence to equilibrium, we will present

a homogenization result (invariance principle) and we will discuss

about the convergence of the gLE dynamics to the (Markovian) Langevin

dynamics, in some appropriate asymptotic limit. The analysis is based on the approximation of the gLE by a

high (and possibly infinite) dimensional degenerate Markovian system,

and on the analysis of the spectrum of the generator of this Markov

process. This is joint work with M. Ottobre and K. Pravda-Starov.

Mon, 07 Feb 2011

12:00 - 13:00
L3

Could Spacetime be Causal Structure Alone?

Fay Dowker
(Imperial College)
Abstract
Abstract: In the continuum the answer to the title question is "no". But if spacetime is atomic then the answer is yes. And it so happens that there is rather compelling circumstantial evidence that spacetime is actually discrete at the Planck scale. So now the question becomes, why if spacetime is discrete should it take the form of a discrete causal structure or *order*? The answer is that if you don't put causal order in fundamentally you don't get it out -- at least that's what known models of "emergent spacetime" indicate. If we want to make life easy for ourselves in quantum gravity, then, we should plump for discrete causal order (a "causal set") as the inner basis for spacetime. That, however raises the spectre of wild nonlocality. I will describe recent progress that shows that this wildness can be tamed. In particular we now have an approximately local action for causal sets and I'll explain what that means.
Mon, 31 Jan 2011

12:00 - 13:00
L3

Branes, Boxes and Black Holes

Toby Wiseman
(Imperial College)
Abstract
Abstract: I will begin by reviewing the use of Ricci flow and the associated Ricci soliton equation to provide constructive numerical algorithms to find static vacuum black holes. I will then describe recent progress to generalize these methods to stationary black holes. I will present new results found using these methods, firstly on stationary black holes in spherical boxes, and secondly, black holes localized on a Randall-Sundrum brane. The latter case hopefully resolves the validity of a phenomenologically striking and important conjecture, and also has relevance to AdS-CFT.
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.
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