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Online Talks

Durham Cathedral

London Mathematical Society Durham Symposium
Non-Perturbative Techniques in Field Theory
Sunday 18th July - Sunday 25th July 2010
List of abstracts
Ofer Aharony (Weizmann Institute) Tuesday 20th July 09:45
Strongly coupled field theories in anti-de Sitter space
I will discuss work in progress on strongly coupled field theories on anti-de Sitter space. These are interesting in their own right, as the anti-de Sitter space provides a natural IR cutoff. They are also interesting in the context of the AdS/CFT correspondence, in two directions. Strongly coupled field theories on D dimensional AdS space can have (D+1) dimensional gravitational duals. And, if such theories appear as part of a gravitational background, they could be dual to conformal field theories in (D-1) dimensions. I will focus on two main examples, the d=4 N=4 SYM theory on AdS4, and confining field theories on AdS space.

Richard Battye (University of Manchester) Friday 23rd July 17:15
Evolution charged domain wall networks
The standard lore of domain wall evolution is that they scaling with the number of walls being inversely proportional to time. We will show how this can be very different is the domain wall forming field is coupled to the an unbroken U(1) field which generates a Noether current. The natural propensity of loops of wall to collapse under their own tension is resisted by the current leading to the possibility of glass-like configurations of walls.

Niklas Beisert (AEI Potsdam) Tuesday 20th July 11:00
Integrability for scattering amplitudes in planar N=4 super Yang-Mills
Tremendous progress in computing perturbative scattering amplitudes in N=4 supersymmetric gauge theory has been made over the past few years. Importantly the planar amplitudes appear to display a dual conformal invariance next to the usual conformal symmetry. Altogether the symmetry enlarges to a Yangian algebra known from the context of integrable models. This infinite-dimensional symmetry might have the power to completely fix the S-matrix by algebraic means. In this talk we review the above developments. We then discuss conformal symmetry for tree and loop scattering amplitudes. It turns out that the free conformal symmetry generators are anomalous which calls for certain deformations to make the symmetries exact. These relate amplitude with different numbers of legs, and thus they contribute substantially to a complete algebraic determination.

Andreas Brandhuber (Queen Mary University of London) Wednesday 21st July 09:45
Surprises in the Wilson loop/Amplitude Duality
MHV Amplitudes in planar N=4 super Yang-Mills are conjectured to be equal to lightlike polygonal Wilson loops at all orders in perturbation theory. In this talk we discuss recent progress and results at two-loop order and at weak coupling. Usually the duality is expressed in terms of four-dimensional quantities. We demonstrate the completely unanticipated fact that the equality continues to hold at two loops through order epsilon in dimensional regularization for the four- and five-particle amplitudes.

Nick Dorey (University of Cambridge ) Wednesday 21st July 11:00
Wall Crossing and Instantons in Compactified Gauge Theory

Jerome Gauntlett (Imperial College London) Thursday 22nd July 09:00
AdS/CMT and Consistent KK Truncations

Rajesh Gopakumar (Harish-Chandra Research Institute) Monday 19th July 09:45
Unravelling the String Dual to the Gaussian Matrix Model
I will give a concrete description of how the string dual to the simplest large N theory - the Gaussian matrix integral - emerges from its Feynman graphs.

Nicolay Gromov (King's College) Wednesday 21st July 11:45
Y-system for AdS/CFT: News, Tests and Tools

Amihay Hanany (Imperial College London) Monday 19th July 17:15
Chiral Operators on the Moduli space of Instantons
The moduli space of instantons has been a subject of many research problems. In this talk we will see some new results on this moduli space, by taking a look at chiral operators.

Derek Harland (Durham University) Friday 23rd July 11:00
Instantons in dimensions greater than 4
Generalisations of the 4-dimensional anti-self-dual Yang-Mills equation to dimensions up to and including 8 have been known since the early eighties. These equations have subsequently found applications in string compactifications, in Donaldson-Thomas theory, and in Kapustin-Witten's work on the geometric Langlands program. In flux compactifications, one is particularly interested in manifolds with torsionful G-structures: I will discuss examples of solutions on such manifolds. For certain kinds of torsion, the instanton equations have interpretation as gradient and Hamiltonian flows.

Roman Jackiw (Massachusetts Institute of Technolog) Friday 23rd July 09:00
The physics of zero energy modes: Fractional Charge
(Joint work with So-Young Pi)
A "Dirac" - type equation, i.e. a matrix equation with first-order derivatives, usually possesses positive- and negative- energy eigenvalues. In the vacuum the former are empty and the latter are filled. However it may happen that when the "Dirac" equation is considered in a topologically non-trivial background, it possesses zero-energy eigenvalues. The question then arises whether in the vacuum these zero-energy states are empty or filled. Analysis of this question results in the conclusion that the charge- or the number- eigenvalue becomes fractional.

Romuald Janik (Jagiellonian University) Tuesday 20th July 17:15
Far from equilibrium plasma and AdS/CFT
I would like to describe the application of the AdS/CFT correspondence to study the dynamics of far from equilibrium plasma.

Andreas Karch (University of Washington ) Thursday 22nd July 16:30
A particle physicist's perspective on topological insulators.
The theory of topological insulators will be reviewed in terms familiar to particle theorists. These tools will be used to describe a novel state of matter that could be thought experimentally, a fractional topological insulator.

David A. Kosower (Institut de Physique Théorique, CEA-Saclay) Monday 19th July 11:45
A Basis for Two-Loop Integrals
I discuss the construction of an integral basis at two loops, both to all orders in the dimensional regulator eps, and for integrals truncated to O(eps). I also discuss a new approach for organizing integration-by-parts equations needed in the construction of such bases.

Prem Kumar (Swansea University) Monday 19th July 11:00
Quantum Phases of k-strings
I will describe aspects of confining k-strings in mass deformed N=4 theory, and in particular, the quantum dynamics on their moduli space.

David Kutasov (University of Chicago) Tuesday 20th July 09:00
a-Maximization, Global Symmetries and RG Flows
I will describe a generalization of the construction of the a-function of hep-th/0312098, which is defined along RG flows and coincides with the central charge a at fixed points, to general F-term perturbations of an arbitrary 3+1 dimensional N=1 SCFT. This construction will be used to argue that the central charge a always decreases along the corresponding RG flows, and for some other applications.

Kimyeong Lee (Korea Institute for Advanced Study) Thursday 22nd July 17:15
Supersymmetric Theories on M2 Branes
I review Nge 5 Superconformal Field Theories in 2+1 dimensional spacetime, and cover our recent works on ABJM model.

Nick Manton (University of Cambridge) Friday 23rd July 09:45
Vortices and complex geometry
I will discuss the interplay of the physics and mathematics of abelian Higgs vortices on a compact Riemann surface. When the surface is large, the vortices behave like particles. When the surface is small, and can only just accommodate the vortices (the Bradlow limit), the vortices reduce to divisors on the Riemann surface, and their fields can be described using classical, holomorphic concepts like abelian differentials. The metric on the 1-vortex moduli space can be computed in both limits.

Michel Peyrard (ENS Lyon) Saturday 24th July 09:00
Talk: Nonlinear excitations as tools to analyze DNA thermodynamics and dynamics.

DNA is not the static object that structural images show. It is a highly dynamical molecule. The base pairs, which encode the genetic information, fluctuate widely. The lifetime of a base pair, i.e. the time during which it stays closed, is only of the order of a few milliseconds. At high temperature some parts of the double helix open locally and form the so called 'denaturation bubbles', which play a role in biological function. When it is viewed at the scale of base pairs, DNA appears as a nonlinear lattice. There are certainly no solitons in DNA but nonlinear localized excitations are nevertheless very helpful to analyze its properties.

Computing the free energy of the 'domain walls', which separate open and closed regions, we can predict the temperature at which the two strands fully separate due to thermal fluctuations (the 'melting' transition of DNA) with a much better accuracy than with the standard methods of statistical physics.

The local fluctuations of the double helix can be described in terms of localized modes (discrete breathers) but establishing a satisfactory model is a challenge because the accurate experiments which can be performed on this molecule impose severe constraints on the models. The analysis of the time scales of the fluctuations led us to a model that sustains a new class of discrete breathers.


[1] M. Peyrard, Nonlinear dynamics and statistical physics of DNA. Nonlinearity 17, R1-R40 (2004)

[2] T. Dauxois, N. Theodorakopoulos and M. Peyrard, Thermodynamic instabilities in one dimension: correlations, scaling and solitons. J. Stat. Phys. 107, 869-891, (2002)

[3] N. Theodorakopoulos, M. Peyrard and R.S. MacKay, Nonlinear structures and thermodynamic instabilities in a one-dimensional lattice system. Phys. Rev. Lett. 93, 258101-1-4 (2004)

[4] M. Peyrard, S. Cuesta Lopez and G. James, Modelling DNA at the mesoscale: a challenge for nonlinear science? Nonlinearity 21, T91-T100 (2008)

Mikhail Polikarpov (Institute for Theoretical and Experimental Physics) Saturday 24th July 11:00
Talk: Effects of strong magnetic field in lattice QCD
In the non-central heavy ion collisions a very strong magnetic field can be generated and the interference of strong and electromagnetic interactions produce various physical effects. We use the chirally invariant lattice Dirac operator to study gluodynamics in the strong magnetic field. The observed effects are: the enhancement of the chiral condensate, magnetization of the vacuum (spins of the virtual quarks turn parallel to the external field), the local generation of the anomalous quark electric dipole moment along the magnetic field, the chiral magnetic effect (a CP-odd generation of the electric current of quarks directed along the magnetic field), existence of nonzero electric conductivity along the direction of the field (the vacuum becomes an anisotropic conductor).

Mukund Rangamani (Durham University) Thursday 22nd July 11:00
Quantum fields in curved spacetime: The strong coupling story

Simon Ross (Durham University) Wednesday 21st July 09:00
Holography for non-relativistic CFTs

Edward Shuryak (Stony Brook University ) Saturday 24th July 11:45
QCD topology and RHIC experiments
The first half of the talk is related with confinement problem and its relation to instantons/dyons/monopoles: one new element is lattice study of the monopole clustering which provides clear evidence of their Bose condensation exactly at Tc. The second tells about several topology-related issues of the RHIC program. QCD sphalerons and RHIC experiment aimed at observing them directly in double-diffractive pp collisions. The so called Magnetic Chiral Effect looks for CP-odd domains inside the QGP produced in heavy ion collisions. Finally, there are evidences of flux tubes preserved in hot matter, confirming a view that near-Tc matter is basically a plasma of magnetic objects.

Jacob Sonnenschein (Tel Aviv University) Thursday 22nd July 09:45
Non-perturbative field theory- from 2d CFT to QCD in four dimensions

Mikhail Stephanov (University of Illinois, Chicago) Thursday 22nd July 11:45
AdS/QCD and Charmonium at Finite Temperature
I shall discuss holographic approach to charmonium and its spectral function at finite temperature in terms of the position and the strength of the complex singularities (quasinormal modes). Within the model, the 'melting' of the J/psi spectral peak occurs at a temperature T~540 MeV, in agreement with lattice results.

Paul Sutcliffe (Durham University) Friday 23rd July 11:45
Skyrmions, instantons and holography
I will describe how the holonomy of Yang-Mills instantons yields exact solutions of a BPS Skyrme model, in which the Skyrme field is coupled to a tower of vector mesons.

Arkady Tseytlin (Imperial College London) Tuesday 20th July 16:30
Superstrings in AdS5 × S5: some perturbative results
I will review some recent results of perturbative computations for superstrings in AdS5 × S5 and their correspondence with Bethe ansatz results for the spectrum. I will also discuss semiclassical approximation for 2-point correlators of string vertex operators.

Dmytro Volin (Penn State University) Tuesday 20th July 11:45
Y-systems and spin chains
There is an intriguing fact that transfer matrices of integrable spin chains and T-functions that follow from the thermodynamic Bethe Ansatz obey the same Hirota equations. It is therefore natural to ask the question if these two originally different objects coincide. We will consider two different examples trying to answer this question. For one case the answer is "yes". For another one the answer is not clear, and there are arguments that favor the negative answer.

Erick Weinberg (Columbia University) Friday 23rd July 16:30
Massless magnetic monopoles

Laurence Yaffe (University of Washington) Saturday 24th July 09:45
Large N volume independence in conformal and confining gauge theories
In the large N limit, gauge theories compactified on Rd-k × (S1)k are independent of the S1 radii provided the theory has unbroken center symmetry.
This implies that a large N gauge theory which, on Rd, flows to an IR fixed point retains the infinite correlation length and other scale invariant properties even when toroidally compactified. Numerical studies to determine the conformal window boundary may, in the large N limit, be performed on one-site lattice models. Large N QCD with massive adjoint fermions, when toroidally compactified, has a rich phase structure with infinitely many phase transitions coalescing in the zero radius limit.

Piljin Yi (Korea Institute for Advanced Study) Monday 19th July 16:30
Holographic Baryons and a Matrix Model