Academic Year 2010/2011
Unless otherwise stated, seminars
will take place in the Cramond Room of the
ICMS
at
the University of Edinburgh.
Please contact the organisers Tim Adamo (UoE) or Richard Davison (HW)
with any questions regarding the seminars.
Wednesday,
29 June 2011
Appleton Tower 2.11
14:30
Imtak Jeon
(Sogang University, Seoul)
We revisit the ideal Bose gas confined in a cubic box, which is
discussed in most of statistical physics textbooks as the simplest bosonic
system. We report that, the isobar of the gas zigzags on the
temperature-volume plane provided the number of particles is finitely large
enough. This demonstrates for the first time, how finite systems can
feature mathematical singularities. The talk is based on papers: Phys.
Rev. A 81 063636 (2010) and New J. Phys. 13 (2011) 033003.
16:00
Kanghoon Lee
(CQuest, Seoul)
While the fundamental object in Riemannian geometry is the
metric, closed string theories put a two-form gauge field and a dilaton on
the same footing as the metric. In this talk we introduce a novel
differential geometry which treats those three objects in a unified manner,
and manifest not only the gauge symmetries (diffeomorphism plus one-form
gauge symmetry) but also the O(D,D) T-duality. We also discuss how to
couple to Yang-Mills theory.
Wednesday,
20 April 2011
Chrystal Macmillan Building Seminar Room 5
14:30
Oliver Rosten
(University of Sussex)
The Exact Renormalization Group (ERG) is a technique which can be fruitfully applied to systems with local interactions that exhibit a large number of degrees of freedom per correlation length. In the first part of the talk I will give a very general overview of the ERG, focussing on its applications in quantum field theory (QFT) and critical phenomena. In the second part I will discuss how a particular extension of the formalism suggests a new understanding of correlation functions in QFTs.
16:00
Francis Dolan
(DAMTP, Cambridge)
The conformal bootstrap, has been fully implemented for d=2 CFTs,
but very little has been achieved in d >2. Part of the difficulty lies in
finding tractable solutions for conformal partial waves, the topic
of my talk.
Wednesday,
6 April 2011
Room 7.01
14:30
Robert Weston
(HW)
I shall describe recent work with J-S Caux, H Konno and M Sorrell in
which we consider the XXZ model in the massless regime. This quantum
spin chain is happily both quantum integrable and experimentally
realisable. I shall describe how the vertex operator approach,
developed originally for the massive antiferromagnetic model, may be
used to find exact lattice form-factors for the massless regime. I
will show how these form-factors may be used to compute contributions
to the longitudinal structure factor. I shall give an explicit
expression for the exact two-particle contribution and present
quantitative evidence for the dominance of this contribution. This
structure factor is directly measurable via neutron scattering
experiments.
16:00
Nicolai Kitanine
(Université de Bourgogne)
Computation of the correlation functions is a central problem in the field of quantum integrable models. It is crucial for effective applications of these models in the condensed matter physics (the associated dynamical structure factors are measurable quantities), but also for better understanding of more fundamental questions about the one-dimensional exactly solvable quantum systems. We study the asymptotic behavior of the correlation functions of the XXZ spin chain in the massless regime. For the equal-time two-point functions the asymptotic expressions can be obtained through the analysis of the form factors, using a simple but very non-trivial identity for hypergeometric series. The main attention will be drawn to the results for the correlation amplitudes and their expressions in terms of some special form factors. It will be shown that these results are quite general and can be easily generalized for a very large class of massless quantum integrable systems.
Wednesday,
23 March 2011
Room 7.01
14:30
Paul de Medeiros
(UoE)
We consider the structure of a simple class of affine toric Calabi-Yau varieties that are defined from quiver representations based on finite eulerian directed graphs (digraphs). Eulerian digraphs can be generated from just a handful of canonical graph-theoretic moves and we describe the effect of each move on the lattice polytopes which encode the associated Calabi-Yau varieties. Some physical applications of the construction will also be discussed in the context of moduli spaces for superconformal gauged linear sigma models and quiver gauge theories based on brane tilings.
16:00
James Sparks
(Oxford)
The path integral of three-dimensional N=2 gauge theories on the three-sphere localizes to a certain type of matrix integral. A large class of N=2 Chern-Simons gauge theories with matter are conjectured to be holographically dual to M-theory on certain Sasaki-Einstein 7-manifolds. I will describe how to compute the M-theory limit (large N and fixed Chern-Simons levels) of the three-sphere partition function for such models, and show in several examples that in this limit the free energy reproduces the expected AdS/CFT result of N^{3/2}/Vol(Y)^{1/2}, where Vol(Y) denotes the volume of a corresponding Sasaki-Einstein metric. This constitutes a new test of the AdS_4/CFT_3 correspondence for a large class of theories.
Wednesday,
9 March 2011
Room 7.01
14:30
James Lucietti
(UoE)
For any spacetime containing an extremal black hole (or in fact any degenerate horizon), one can define a limiting process which leads to an associated space-time called the near-horizon geometry. Classifying such near-horizon geometries is necessary for solving the corresponding uniqueness/classification problem for extremal black holes, which has important implications within string theory and the gauge/gravity duality. I will review progress on classifying such near-horizon geometries in four and higher spacetime dimensions, focusing on solutions to the vacuum Einstein equations.
16:00
Paul Zinn-Justin
(Université Pierre et Marie Curie, Paris)
In this talk we shall demonstrate how simple tools coming from exactly solvable two-dimensional lattice models can be applied to problems in enumerative combinatorics. Specifically, we revisit Izergin's determinant formula for the partition function of the six-vertex model with Domain Wall Boundary Conditions. We show how it can be turned into a remarkably simple form in the homogeneous limit. We apply it to prove a 1983 conjecture of Mills, Robbins and Rumsey on the enumeration of Alternating Sign Matrices and Descending Plane Partitions. This is joint work with R. Behrend and P. Di Francesco.
Wednesday,
23 February 2011
Room 7.01
13:00
Marika Taylor
(Universiteit van Amstredam)
There has recently been considerable discussion of holographic backgrounds with Schrodinger and Lifshitz symmetry, motivated by condensed matter applications. Since the bulk spacetimes are not asymptotically AdS, there are however many subtleties in setting up a holographic dictionary. In this talk we will argue that Schrodinger spacetimes (along with some realizations of Lifshitz) can be understood in terms of deformations of conformal field theories which break the relativistic scaling symmetry, but preserve an anisotropic/non-relativistic scale symmetry. We will highlight how this fact restricts which condensed matter systems can be well modeled holographically, and we will briefly discuss how the entropy of Schrodinger black holes (so-called null warped black holes) in three dimensions can be understood in this framework.
14:30
Nick Manton
(Cambridge)
The equations for Abelian Higgs vortices (at critical coupling) on a plane or a more general surface are generally not integrable, but for vortices on a hyperbolic plane of curvature -1/2 they are. This talk will present (almost explicit) vortex solutions on certain compact hyperbolic surfaces. Also to be discussed are two asymptotically solvable problems for vortices: the metric on vortex moduli space for large surfaces with small curvature, and the vortices and their moduli space on a small surface where the vortices are about to dissolve (and the equations linearize).These results (obtained with N. Rink and with N. Romao) bring vortex theory closer to classical results on the complex and metric geometry of Riemann surfaces.
This talk will take place within the North British Mathematical Physics Seminar series
Wednesday,
16 February 2011
at
15:30
Appleton Tower Room 2.14
Ben Craps
(Brussels)
Wednesday,
19 January 2011
Room 7.01
14:30
Volker Schomerus
(DESY)
Supersymmetric 2-dimensional statistical systems play a
central role in modern mathematical physics, most notably
for the string theoretic description of 4-dimensional
gauge theories. These systems possess many intriguing
features which distinguish them from their bosonic
counterparts. As one striking example I shall explain
how classical geometries can emerge from supermagnets.
Potential applications, in particular to the AdS/CFT
correspondence, will be sketched.
16:00
Christian Saemann
(HW)
I will present an ADHMN-like construction which generates self-dual string solutions to the effective M5-brane worldvolume theory from solutions to the Basu-Harvey equation.
Wednesday,
15 December 2010
14:30
Richard Szabo
(HW)
We describe the statistical mechanics of a melting crystal in three
dimensions, and its relationships with diverse topics in mathematical
physics. On the mathematics side, the model is connected to the
combinatorics of plane partitions and the enumeration of Donaldson-Thomas
invariants in algebraic geometry. On the physics side, it is related to
certain integrable hierarchies, matrix models, Chern-Simons gauge theory,
and a toy model of quantum gravity in six dimensions. Its partition
function can also be computed by enumerating the contributions from
noncommutative instantons to a six-dimensional topological gauge theory;
this yields an interpretation of the melting crystal model as a
discretization of six-dimensional spacetime at the Planck scale. We also
describe analogous relations between a melting crystal model in two
dimensions and N=4 supersymmetric Yang-Mills theory in four dimensions.
16:00
Jan Gutowski
(King's College London)
Spinorial geometry techniques have enabled a systematic classification
of many types of supergravity solutions. I will describe recent progress
made in using these techniques to classify the geometry of
supersymmetric black hole event horizons, concentrating on the case
of ten dimensional heterotic supergravity. New examples of
supersymmetric horizons have been found, some of which have unusual
topologies.
Tuesday,
7 December 2010
at
17:00
Room 4.01
Debashis Ghoshal
(Jawaharlal Nehru University, New Delhi)
Some of the perturbative vacua of open string theory are known to be unstable. They decay to other (meta-)stable vacua. We will consider the dynamics of this relaxation process (decay). In particular, the equation that describes an inhomogeneous decay turns out to be a variant of a non-linear partial differential equation that appears in many other areas. We will point out their similarities and differences.
Wednesday,
1 December 2010
14:30
Arjun Bagchi
(UE)
In this talk I develop techniques of non-relativistic quantum conformal symmetry in two dimensions.
Correlation functions and other details of the representations like null vectors are looked at.
The answers are obtainable by looking exclusively at the non-relativistic algebra and
are also derivable as a limit of the relativistic answers. The matching of the two different ways of calculation
gives a non-trivial check of the correctness of the results.
We also briefly talk about the gravitational realization of the non-relativistic system in terms of
Topologically Massive Gravity.
16:00
Yang-Hui He
(Oxford)
We investigate certain arithmetic properties of field theories. In particular, we study the vacuum structure of supersymmetric gauge theories as algebraic varieties over number fields of finite characteristic. Parallel to the Plethystic Programme of counting the spectrum of operators from the complex geometry, we investigate the Hasse-Weil zeta functions and the associated Dirichlet expansions. We find curious dualities wherein the geometrical properties and asymptotic behaviour of one gauge theory is governed by the number theoretic nature of another.
Wednesday,
24 November 2010
at
15:00
James Clerk Maxwell Building Room 5215
Aristomenis Donos
(Imperial College)
Condensed matter systems at quantum critical points can be described by strongly coupled field theories exhibiting anisotropic scale invariance. Lifshitz geometries been proposed to be holographic duals to these theories. I will discuss top down constructions of Lifshitz geometries in Type IIB and D=11 dimensional supergravities.
This is a colloquium of the Department of Physics at Heriot-Watt
Wednesday,
17 November 2010
at
15:30
Postgraduate Centre Auditorium
Gerard ‘t Hooft
(University of Utrecht)
In Physics, black holes are known as extremely dense forms of
matter, of which, from the outside, only the gravitational force can be
detected. Astronomers observe such object ate various spots in the Universe.
When in laboratories on earth elementary particles are made to collide with
the strongest possible force, these collisions are by far not energetic
enough to produce black holes. However, we can try to imagine collisions
that are so energetic that black holes do form, and then ask ourselves what
exactly might happen then. The question is important because it turns out
that our theoretical understanding falls short at this point. The
gravitational force is so special that all beautiful theories we have today
about the particles and the forces between them cannot describe it. Do black
holes obey the laws of quantum mechanics? Are black holes also subatomic
particles and vice versa? If so, our theories must be revised. This can lead
to fundamental new insights about very basic features in physics, and give
us new tools to describe space, time, and matter.
Wednesday,
3 November 2010
Room 7.01
14:30
Patricia Ritter
(UE)
I will give a brief review of spacelike warped AdS_3 and its geometry, before describing the black hole quotients that can be obtained by identification along Killing vectors $\partial_\theta$. We will see that these can be conveniently written in terms of different parametrisations, in particular in accelerating and Poincaré coordinates. I will then show various limits of the black hole phase-space (parametrised by $(T_L, T_R)$) that can be obtained by requiring that $\partial_\theta$ have a finite non-zero limit. These will be seen to be nothing more than the self-dual solution in accelerating coordinates for non-extremal black holes, in Poincaré coordinates for the extremal ones. We can also obtain a "vacuum" limit, written as warped AdS$_3$ in Poincaré coordinates with a periodic proper time identification.
16:00
Costis Papageorgakis
(King's College)
Using 3-algebras we obtain a nonabelian system of equations that furnish a representation of the (2,0)-supersymmetric tensor multiplet. The on-shell conditions are quite restrictive so that the system can be reduced to five-dimensional super-Yang-Mills theory along with six-dimensional abelian (2,0) tensor multiplets. Possible applications to D4-branes and M5-branes are discussed.
Wednesday,
27 October 2010
Room 12.18
14:30
Matthias Ihl
(Universidade Federal do Rio de Janeiro)
I will first discuss some new results concerning the phenomenology of pions and vector mesons in a model of flavor chiral symmetry breaking in the Klebanov-Witten background, recently introduced by Kuperstein and Sonnenschein. I will outline the calculation of electromagnetic form factors in this model. Here, our main result is the pion form factor, which matches available experimental data surprisingly well. In the second part of the talk, I will present our results and discuss ongoing research relating to the spectra of scalar and vector mesons in the Dymarsky-Kuperstein-Sonnenschein model, which geometrically realizes flavor chiral symmetry breaking in the Klebanov-Strassler model, i.e. a non-conformal deformation of the Klebanov-Witten background. Interestingly, the lightest scalar meson, associated with fluctuations of the background gauge field, is lighter than the lightest vector meson in this model, which potentially has interesting implications for holographic nuclear physics.
16:00
Geoffrey Compère
(University of Amsterdam)
A microscopic analysis of the extremal Kerr black hole will be initiated
using a brane construction. The key observation that will be presented
is the following: the magnetically charged spinning one-brane in minimal
supergravity admits a decoupling limit which interpolates smoothly
between the self-dual null orbifold of AdS_3 \times S^2 and the
near-horizon region of the extremal Kerr black hole times a circle. This
solution will be used to find the specific deformations of the CFT dual
to AdS_3 \times S^2 which correspond to the supergravity deformation
leading to the Kerr geometry.
Wednesday,
6 October 2010
Room 7.01
14:30
Christoph Nölle
(Uni Hannover/UE)
I will discuss heterotic string theory on manifolds of the form AdS4
times a 6-dimensional nearly Kaehler manifold. Both the gravitino
Killing spinor equation and the heterotic Bianchi identity have
natural solutions on these spaces, whereas the dilatino equation
appears to be incompatible with them. I present two approaches to
solve this problem.
16:00
Mukund Rangamani
(Durham)
I will discuss some curious features associated with the
dynamics of conformal field theories on AdS space times. In
particular, I will explore the dynamics of N=4 SYM at weak and strong
coupling in global AdS4.
