Triangle Seminars
August 2006
Wed
30 Aug 2006
Black Holes, Information Paradox and AdS/CFT
David Lowe
(Brown)
Thu
24 Aug 2006
The seminar has been moved to Wednesday
📍 London
Thomas Quella
(KCL)
Wed
23 Aug 2006
Supergroup WZW models
📍 London
Thomas Quella
(KCL)
Abstract:
We present recent progress on the solution of WZW models based on type I supergroups. The spectrum is derived in the minisuperspace limit and extrapolated to the full WZW model. The main feature is the occurence of indecomposable non-chiral representations which are responsible for the logarithmic behaviour of correlation functions. The talk will consist of three parts: 1. Representation theory of Lie superalgebras, 2. general type I supergroup WZW models and 3. particularities of the PSU(1,1/2) WZW model. If the audience has enough stamina we can also discuss certain aspects of special marginal deformations of the PSU(1,1/2) WZW model which describe AdS(3)xS(3) with mixed RR and NS fluxes.
We present recent progress on the solution of WZW models based on type I supergroups. The spectrum is derived in the minisuperspace limit and extrapolated to the full WZW model. The main feature is the occurence of indecomposable non-chiral representations which are responsible for the logarithmic behaviour of correlation functions. The talk will consist of three parts: 1. Representation theory of Lie superalgebras, 2. general type I supergroup WZW models and 3. particularities of the PSU(1,1/2) WZW model. If the audience has enough stamina we can also discuss certain aspects of special marginal deformations of the PSU(1,1/2) WZW model which describe AdS(3)xS(3) with mixed RR and NS fluxes.
Posted by: KCL
Wed
9 Aug 2006
Tensor C(star)-categories with non-simple units
📍 London
Pasquale Zito
(KCL)
June 2006
Tue
27 Jun 2006
LHC, M theory and the Hierarchy Problem
Bobby Acharya
(ICTP Trieste)
Mon
26 Jun 2006
Natural Inflation after WMAP
Katie Freese
(Michigan)
Mon
26 Jun 2006
Black Hole Entropy in String Theory
Atish Dabholkar
(Tata Institute)
Mon
26 Jun 2006
Superconducting Strings, Black Holes and Other Matters
Tanmay Vachaspati
(Case Western)
Fri
16 Jun 2006
Continued fractions, non-commutative boundaries and Einstein equations
📍 London
Yuri Manin
(Northwestern University)
Abstract:
This is a Hardy lecture of the LMS. It is embedded into a wider program. Please consult the webpage http://www.lms.ac.uk/meetings/16june06.html for details.
This is a Hardy lecture of the LMS. It is embedded into a wider program. Please consult the webpage http://www.lms.ac.uk/meetings/16june06.html for details.
Posted by: KCL
Thu
15 Jun 2006
Properties of the type II effective action
Jorge Russo
(University of Barcelona)
Abstract:
The exact string coupling dependence of higher derivative
terms in the type IIA and type IIB effective action is highly constrained by a combination of duality symmetries and by results from perturbative string theory. For example, we show that terms of the form D to the 2k times R to the 4th in type IIA theory should receive no perturbative contributions beyond genus k (k greater than 0). We also propose that the exact modular functions of general type IIB higher derivative terms are determined by a Poisson equation on the fundamental domain of the moduli space.
The exact string coupling dependence of higher derivative
terms in the type IIA and type IIB effective action is highly constrained by a combination of duality symmetries and by results from perturbative string theory. For example, we show that terms of the form D to the 2k times R to the 4th in type IIA theory should receive no perturbative contributions beyond genus k (k greater than 0). We also propose that the exact modular functions of general type IIB higher derivative terms are determined by a Poisson equation on the fundamental domain of the moduli space.
Posted by: IC
Tue
13 Jun 2006
Complex Quartic Hamiltonians
Carl Bender
(Washington University in St. Louis)
Mon
12 Jun 2006
Excited Giant Gravitons
Robert de Mello Koch
(SIAS)
Mon
12 Jun 2006
A surgery for generalized complex 4-manifolds
Gil Cavalcanti
(Oxford)
Abstract:
One of the few known obstructions for a 1-connected 4-
manifold to admit a symplectic structure is given by Taubes theorem:
if b_+ is greater than two, then such a manifold has a nonvanishing Seiberg–Witten
invariant. It is only natural to ask whether the same holds for
generalized complex manifolds, as introduced by Hitchin, which are a
simultaneous generalization of symplectic and complex manifolds.
I will introduce a surgery for generalized complex manifolds whose input
is a symplectic 4-manifold containing a symplectic 2-torus with trivial
normal bundle and whose output is a 4-manifold endowed with a
generalized complex structure exhibiting type change along a 2-torus.
I will use this surgery to produce an example of a generalized complex
manifold with vanishing Seiberg–Witten invariants and hence which does
not admit complex or symplectic structures.
One of the few known obstructions for a 1-connected 4-
manifold to admit a symplectic structure is given by Taubes theorem:
if b_+ is greater than two, then such a manifold has a nonvanishing Seiberg–Witten
invariant. It is only natural to ask whether the same holds for
generalized complex manifolds, as introduced by Hitchin, which are a
simultaneous generalization of symplectic and complex manifolds.
I will introduce a surgery for generalized complex manifolds whose input
is a symplectic 4-manifold containing a symplectic 2-torus with trivial
normal bundle and whose output is a 4-manifold endowed with a
generalized complex structure exhibiting type change along a 2-torus.
I will use this surgery to produce an example of a generalized complex
manifold with vanishing Seiberg–Witten invariants and hence which does
not admit complex or symplectic structures.
Posted by: IC
Fri
9 Jun 2006
The structure of semi-simple topological field theories
Constantin Teleman
(Cambridge)
Thu
8 Jun 2006
Multi-center attactors
Eric Gimon
(Berkeley)
Tue
6 Jun 2006
Equilibrium Thermodynamics for Quantum Systems
Dorje Brody
(Imperial)
Tue
6 Jun 2006
Supersymmetric Gauge Theories in Twistor Space
David Skinner
(Oxford)
Mon
5 Jun 2006
Singularities of Lagrangian mean curvature flow
Andre Neves
(Princeton University)
Abstract:
I will talk about the possibilities of using mean curvature flow to
deform a Lagrangian submanifold into an area-minimizing Lagrangian
(known also as SLag). More precisely, I will show that finite time
singularities are unavoidable, i.e., they appear for a large class of
stable initial conditions. Then, I will give the optimal theorem
regarding the structure of the tangent flow at a singularity.
I will talk about the possibilities of using mean curvature flow to
deform a Lagrangian submanifold into an area-minimizing Lagrangian
(known also as SLag). More precisely, I will show that finite time
singularities are unavoidable, i.e., they appear for a large class of
stable initial conditions. Then, I will give the optimal theorem
regarding the structure of the tangent flow at a singularity.
Posted by: IC
Thu
1 Jun 2006
Extended supersymmetric nonlinear sigma-models on cotangent bundles of Kahler manifolds: Superspace formulations, gauging and superpotentials
Sergei Kuzenko
(Perth, Australia)
Abstract:
Among the very first examples of hyper-Kahler manifolds given by Calabi in 1979, there were the cotangent bundles of complex projective spaces, T-star-CPn. Later on, many more examples of hyper-Kahler metrics on cotangent bundles of Kahler manifolds were shown to exist. Finally, Kaledin (1997) and Feix (1999) proved that a real-analytic Kahler metric on a complex manifold M can always be extended to a hyper-Kahler metric in a neighborhood of M in T-star-M. Although these mathematical proofs are rather technical and involved, there exists a streamlined physical construction which leads to the same results and is based on the concept of supersymmetry. As is well-known, four- and five-dimensional N = 2 supersymmetric nonlinear sigma-models possess the property that their target spaces are hyper-Kahler manifolds. The physical construction consists of providing a manifestly N = 2 supersymmetric nonlinear sigma-model whose target space can be shown to be (a neighborhood of the zero section in) the cotangent bundle T-star-M of a Kahler manifold M. This talk will review the salient properties of such supersymmetric nonlinear sigma-models with eight supercharges.
Among the very first examples of hyper-Kahler manifolds given by Calabi in 1979, there were the cotangent bundles of complex projective spaces, T-star-CPn. Later on, many more examples of hyper-Kahler metrics on cotangent bundles of Kahler manifolds were shown to exist. Finally, Kaledin (1997) and Feix (1999) proved that a real-analytic Kahler metric on a complex manifold M can always be extended to a hyper-Kahler metric in a neighborhood of M in T-star-M. Although these mathematical proofs are rather technical and involved, there exists a streamlined physical construction which leads to the same results and is based on the concept of supersymmetry. As is well-known, four- and five-dimensional N = 2 supersymmetric nonlinear sigma-models possess the property that their target spaces are hyper-Kahler manifolds. The physical construction consists of providing a manifestly N = 2 supersymmetric nonlinear sigma-model whose target space can be shown to be (a neighborhood of the zero section in) the cotangent bundle T-star-M of a Kahler manifold M. This talk will review the salient properties of such supersymmetric nonlinear sigma-models with eight supercharges.
Posted by: IC
Thu
1 Jun 2006
Time Dependent AdS/CFT Proposal and Spacetime Singularities
Chong-Sun Chu
(Durham)
Thu
1 Jun 2006
Quasi-linear Stokes Phenomenon for tronque Painlevee Transcendents: The Riemann-Hilbert approach
Alexander Its
(Purdue)
Thu
1 Jun 2006
Field Theory for Distribution Functions in Disordered Conductors
Vladimir Yudson
(Institute for Spectroscopy RAS)
May 2006
Fri
26 May 2006
The AdS/CFT correspondence and four point functions
Hugh Osborn
(Cambridge)
Abstract:
The application of the AdS/CFT correspondence in the calculation of four point functions for
chiral primary operators in the large N limit for maximal superconformal gauge theories is
reviewed. It is shown how the results satisfy certain constraints, motivated by our
understanding from string theory of the spectrum of operators in the large N limit, which allow
a construction of the four point function for any half BPS chiral primary operator at large N.
The application of the AdS/CFT correspondence in the calculation of four point functions for
chiral primary operators in the large N limit for maximal superconformal gauge theories is
reviewed. It is shown how the results satisfy certain constraints, motivated by our
understanding from string theory of the spectrum of operators in the large N limit, which allow
a construction of the four point function for any half BPS chiral primary operator at large N.
Posted by: quella
Fri
26 May 2006
The Lagrangian Origin of MHV Rules
Paul Mansfield
(Durham)
Thu
25 May 2006
Classical and Quantum Gravity Scientific Meeting
📍 London
Various speakers
(various institutes)
Abstract:
Members of the Editorial Board of Classical and Quantum Gravity will be convening for their annual meeting in London in May and will be taking the opportunity to hold a one day conference to present and discuss their latest research. The meeting will cover the broad range of subjects represented on the Board. Some external speakers have also been invited. The details of the program are available here: http://www.mth.kcl.ac.uk/events/theorphysics/program-25-5-06.pdf (copy link into your browser).
Members of the Editorial Board of Classical and Quantum Gravity will be convening for their annual meeting in London in May and will be taking the opportunity to hold a one day conference to present and discuss their latest research. The meeting will cover the broad range of subjects represented on the Board. Some external speakers have also been invited. The details of the program are available here: http://www.mth.kcl.ac.uk/events/theorphysics/program-25-5-06.pdf (copy link into your browser).
Posted by: KCL
Wed
24 May 2006
Gauge/Gravity Dualities and Dipole Deformations
Radu Tatar
(Liverpool)
Wed
24 May 2006
Symmetry and the Monster
📍 London
Mark Ronan
(University of Illinois, Chicago)
Abstract:
See http://www.ucl.ac.uk/lims/new_AllEvents.htm for details!
See http://www.ucl.ac.uk/lims/new_AllEvents.htm for details!
Posted by: KCL
Wed
24 May 2006
The Monster and String Theory
📍 London
Katrin Wendland
(Warwick Mathematics Institute)
Abstract:
See http://www.ucl.ac.uk/lims/new_AllEvents.htm for details!
See http://www.ucl.ac.uk/lims/new_AllEvents.htm for details!
Posted by: KCL
Mon
22 May 2006
Test
Test Test
(Test)
Abstract:
Test
Test
Posted by: quella
Mon
22 May 2006
Calabi-Yau algebras
Raphael Rouquier
(Leeds University and Jussieu, Paris)
Fri
19 May 2006
Brane Power
Tim Hollowood
(Swansea)
Abstract:
D-branes are considered by the general particle physics
community as the arcane inventions of the initiated having no
relevance to even semi-realistic QFTs. In this seminar I want to
provide compelling evidence that the domain walls of the simplest
supersymmetric extension of QCD are D-branes for the confining string
of the theory. Conventional D-brane technology then leads to a
very intriguing result for the forces between the domain walls which
suggests some underlying but unknown magic is at work.
(based on hep-th/0505213,0601150)
D-branes are considered by the general particle physics
community as the arcane inventions of the initiated having no
relevance to even semi-realistic QFTs. In this seminar I want to
provide compelling evidence that the domain walls of the simplest
supersymmetric extension of QCD are D-branes for the confining string
of the theory. Conventional D-brane technology then leads to a
very intriguing result for the forces between the domain walls which
suggests some underlying but unknown magic is at work.
(based on hep-th/0505213,0601150)
Posted by: IC
Thu
18 May 2006
Exploring the Landscape of Flux Vacua
Gianguido Dall'Agata
(CERN)
Abstract:
I will discuss some features of string theory flux vacua that have not been explored before. Inspired by the analogy with the 4-dimensional black-hole solutions, I will show that the moduli fixing by fluxes can be described by an attractor mechanism. The discussion will be mainly focussed on non-Kaeheler attracting manifolds. I will then describe the general features of the domain-wall solutions interpolating between different vacua, explaining the vacua resolution by tunnelling and the (meta)stability properties of de Sitter uplifts.
I will discuss some features of string theory flux vacua that have not been explored before. Inspired by the analogy with the 4-dimensional black-hole solutions, I will show that the moduli fixing by fluxes can be described by an attractor mechanism. The discussion will be mainly focussed on non-Kaeheler attracting manifolds. I will then describe the general features of the domain-wall solutions interpolating between different vacua, explaining the vacua resolution by tunnelling and the (meta)stability properties of de Sitter uplifts.
Posted by: QMW
Thu
11 May 2006
The string field theory of a point
📍 London
R. C. Penner
(USC, Los Angeles)
Wed
10 May 2006
Critical behavior in random matrix models
Arno Kuijlaars
(Leuven)
Abstract:
I will discuss the behavior of eigenvalues of Hermitian random matrices in certain critical regimes, related to possible changes in the number of intervals in the limiting spectrum as the size of the matrices tends to infinity. In the critical regimes local eigenvalue correlation functions are described by Painleve transcendents.
I will discuss the behavior of eigenvalues of Hermitian random matrices in certain critical regimes, related to possible changes in the number of intervals in the limiting spectrum as the size of the matrices tends to infinity. In the critical regimes local eigenvalue correlation functions are described by Painleve transcendents.
Posted by: brunel
Wed
10 May 2006
D-branes and matrix factorisations
Matthias Gaberdiel
(ETH)
Wed
10 May 2006
TBA
Esperanza Lopez
(Madrid)
Mon
8 May 2006
T B A
Nick Warner
(CERN and UCLA)
Fri
5 May 2006
Spectral Curves and Langlands Duality
Nigel Hitchin
(Oxford)
Fri
5 May 2006
Heteroric and Common Sector Supersymmetric Backgrounds
George Papadopoulos
(KCL)
Fri
5 May 2006
Geometric Langlands according to Kapustin and Witten
Nigel Hitchin
(Oxford)
Thu
4 May 2006
Tensors, Hypers, and String Loop-Corrected Moduli Spaces
Frank Saueressig
(Utrecht)
Thu
4 May 2006
T-Folds and Non-Geometric String Backgrounds
Chris Hull
(Imperial)
Wed
3 May 2006
Langlands Journal Club
Bogdan Stefanski
(Imperial)
Wed
3 May 2006
Matrix Models and Noncommutative Field Theory
Richard Szabo
(Herriot Watt Edinburgh)
April 2006
Thu
27 Apr 2006
Strings as Multi-Particle States of Quantum Sigma-Models
Vladimir Kazakov
(Polytechnique)
Abstract:
In the context of integrability in AdS/CFT correspondence, we construct the Green-Schwarz-Metsaev-Tseytlin supersting in the S(5) x R(1) sector, from a set of physical particles on a circle in the integrable 1+1D sigma-model with Zamolodchikov's S-matrix. We reproduce, in the limit of high density of the particles, all finite gap KMMZ solutions for classical strings and the quantum AFS string Bethe ansatz equations, as an approximation to our construction.
In the context of integrability in AdS/CFT correspondence, we construct the Green-Schwarz-Metsaev-Tseytlin supersting in the S(5) x R(1) sector, from a set of physical particles on a circle in the integrable 1+1D sigma-model with Zamolodchikov's S-matrix. We reproduce, in the limit of high density of the particles, all finite gap KMMZ solutions for classical strings and the quantum AFS string Bethe ansatz equations, as an approximation to our construction.
Posted by: IC
Thu
27 Apr 2006
Gauge/Gravity Duals and Generalized Complex Geometry
Michela Petrini
(CPHT)
Tue
25 Apr 2006
Hypermultiplets and Topological Strings
Martin Rocek
(Stony Brook)
Mon
24 Apr 2006
T B A
Martin Rocek
(SUNY Stony Brook)
Thu
20 Apr 2006
Towards the String Dual of N=1 SQCD-like Theories
Angel Paredes
(Polytechnique)
Abstract:
I will discuss the construction supergravity plus branes solutions dual to 4d N=1 SQCD with a quartic superpotential. The geometries depend on the ratio Nf/Nc which is kept of order one. I will show how some field theory features like R-symmetry breaking, Seiberg duality, Wilson loops and pair creation, running of couplings and domain walls are encoded in the solutions.
I will discuss the construction supergravity plus branes solutions dual to 4d N=1 SQCD with a quartic superpotential. The geometries depend on the ratio Nf/Nc which is kept of order one. I will show how some field theory features like R-symmetry breaking, Seiberg duality, Wilson loops and pair creation, running of couplings and domain walls are encoded in the solutions.
Posted by: IC
Thu
13 Apr 2006
Matrix Description of a Big Bang Singularity
Ben Craps
(Amsterdam)
Wed
12 Apr 2006
Algebras in Tensor Categories and Conformal Field Theory
Ingo Runkel
(KCL)
March 2006
Thu
30 Mar 2006
Solving the open string field theory
Martin Schnabl
(CERN)
Abstract:
I will describe a new formulation of Witten's open bosonic string field
theory based on non-standard world-sheet parametrization. The theory
dramatically simplifies and the long-searched-for tachyon vacuum can be
explicitly constructed. This allows us to find a proof for one of the
Sen's conjectures relating the energy of the tachyon solution to the
tension of the D25-brane.
I will describe a new formulation of Witten's open bosonic string field
theory based on non-standard world-sheet parametrization. The theory
dramatically simplifies and the long-searched-for tachyon vacuum can be
explicitly constructed. This allows us to find a proof for one of the
Sen's conjectures relating the energy of the tachyon solution to the
tension of the D25-brane.
Posted by: IC
Thu
30 Mar 2006
K-string: a Mini Review
Adi Armoni
(Swansea)
Mon
27 Mar 2006
Branch points in the complex energy plane
Ingrid Rotter
(Max Planck Institute Dresden)
Abstract:
The Hamiltonian of an open quantum system is non-Hermitian. Its eigenvalues and eigenfunctions are complex and energy dependent. They determine the spectroscopic properties of the system. The eigenvalues may cross in the complex energy plane. The crossing points are branch points that separate the scenario with avoided level crossings from that without any crossing in the complex energy plane. Mathematically, the first case is characterized by level repulsion, the second one by widths bifurcation. The topology of the branch points is different from that of diabolic points: the geometric phase is twice the Berry phase. Physically, the branch points in the complex energy plane cause some stabilization of the system and reduce the phase rigidity of the scattering wave function.
The Hamiltonian of an open quantum system is non-Hermitian. Its eigenvalues and eigenfunctions are complex and energy dependent. They determine the spectroscopic properties of the system. The eigenvalues may cross in the complex energy plane. The crossing points are branch points that separate the scenario with avoided level crossings from that without any crossing in the complex energy plane. Mathematically, the first case is characterized by level repulsion, the second one by widths bifurcation. The topology of the branch points is different from that of diabolic points: the geometric phase is twice the Berry phase. Physically, the branch points in the complex energy plane cause some stabilization of the system and reduce the phase rigidity of the scattering wave function.
Posted by: CityU
Thu
23 Mar 2006
Green-Schwarz Strings in TsT-transformed backgrounds
Sergey Frolov
(AEI)
Abstract:
We consider classical strings propagating in a background generated by a sequence of TsT
transformations. We describe a general procedure to derive the Green-Schwarz action for strings. We show
that the U(1) isometry variables of the TsT-transformed background are related to the isometry variables
of the initial background in a universal way independent of the details of the background. This allows us
to prove that strings in the TsT-transformed background are described by the Green-Schwarz action for
strings in the initial background subject to twisted boundary conditions. Our construction implies that a
TsT transformation preserves integrability properties of the string sigma model. We discuss in detail type
IIB strings propagating in the TsT-transformed AdS(5) x S(5) space-time and find the twisted boundary
conditions for bosons and fermions. We also discuss string zero modes whose dynamics is governed by a
fermionic generalization of the integrable Neumann model.
We consider classical strings propagating in a background generated by a sequence of TsT
transformations. We describe a general procedure to derive the Green-Schwarz action for strings. We show
that the U(1) isometry variables of the TsT-transformed background are related to the isometry variables
of the initial background in a universal way independent of the details of the background. This allows us
to prove that strings in the TsT-transformed background are described by the Green-Schwarz action for
strings in the initial background subject to twisted boundary conditions. Our construction implies that a
TsT transformation preserves integrability properties of the string sigma model. We discuss in detail type
IIB strings propagating in the TsT-transformed AdS(5) x S(5) space-time and find the twisted boundary
conditions for bosons and fermions. We also discuss string zero modes whose dynamics is governed by a
fermionic generalization of the integrable Neumann model.
Posted by: IC
Thu
23 Mar 2006
Kaluza-Klein Holography
Kostas Skenderis
(Amsterdam)
Wed
22 Mar 2006
The Higher Spin/CFT Correspondence
Paul Heslop
(DAMTP)
Wed
22 Mar 2006
D-branes in Field Theory
📍 London
David Tong
(Cambridge)
Wed
22 Mar 2006
Correlation functions in integrable spin-chains 3
Michio Jimbo
(Tokyo University)
Abstract:
Please follow this link for details: http://www.city.ac.uk/sems/mathematics/speciallectures.html
Please follow this link for details: http://www.city.ac.uk/sems/mathematics/speciallectures.html
Posted by: CityU
Mon
20 Mar 2006
Correlation functions in integrable spin-chains 2
Michio Jimbo
(Tokyo University)
Abstract:
Please follow this link for details: http://www.city.ac.uk/sems/mathematics/speciallectures.html
Please follow this link for details: http://www.city.ac.uk/sems/mathematics/speciallectures.html
Posted by: CityU
Fri
17 Mar 2006
Gravity duals of field theory vacua
Marika Taylor
(Amsterdam)
Abstract:
In the first part of the talk we discuss how to construct
geometries sourced by branes carrying general condensates. As an example
we consider fundamental strings carring fermion bilinear condensates.
Dualizing to the D1-D5 system these correspond to the missing geometries
needed to account for all black hole microstates in the fuzzball
conjecture. In the second half of the talk we discuss new results in
extracting field theory data from (asymptotically AdS) geometries. These
methods can be used to show that the D1-D5 geometries do indeed correspond
to R vacua with all the requisite properties.
In the first part of the talk we discuss how to construct
geometries sourced by branes carrying general condensates. As an example
we consider fundamental strings carring fermion bilinear condensates.
Dualizing to the D1-D5 system these correspond to the missing geometries
needed to account for all black hole microstates in the fuzzball
conjecture. In the second half of the talk we discuss new results in
extracting field theory data from (asymptotically AdS) geometries. These
methods can be used to show that the D1-D5 geometries do indeed correspond
to R vacua with all the requisite properties.
Posted by: IC
Thu
16 Mar 2006
Intersecting Brane Worlds: a Possible Path from String Theory to Particle Physics
Rodolfo Russo
(QMW)
Abstract:
I will discuss the main features of the string
compactifications with magnetized (or equivalently
intersecting) D-branes and explain why they represent a
very interesting setup for phenomenological
applications. In particular, I will discuss how to use string techniques to systematically derive brane world effective actions for models with magnetized (or equivalently intersecting) D-branes.
I will discuss the main features of the string
compactifications with magnetized (or equivalently
intersecting) D-branes and explain why they represent a
very interesting setup for phenomenological
applications. In particular, I will discuss how to use string techniques to systematically derive brane world effective actions for models with magnetized (or equivalently intersecting) D-branes.
Posted by: QMW
Wed
15 Mar 2006
Black hole partition functions and duality
📍 London
Thomas Mohaupt
(Liverpool)
Wed
15 Mar 2006
Correlation functions in integrable spin-chains 1
Michio Jimbo
(Tokyo University)
Abstract:
Please follow this link for details: http://www.city.ac.uk/sems/mathematics/speciallectures.html
Please follow this link for details: http://www.city.ac.uk/sems/mathematics/speciallectures.html
Posted by: CityU
Wed
15 Mar 2006
M-theory on the Orbifold (C'2 mod Z_N)
Andre Lukas
(Oxford)
Wed
15 Mar 2006
Random matrices with independent entries
Giovanni Cicuta
(Parma)
Abstract:
The algorithm by M.Bauer and O.Golinelli to evaluate the moments of the spectral density of the incident matrix of random graphs is very useful also for other matrix ensembles: real symmetric, real anti-symmetric, real, laplacian, Wishart,... In most cases it may efficiently be performed by computer. The moments thus evaluated presumably will be useful to complement numerical simulations. In the large n limit, they are a transparent way to examine possible n-dependent rescaling then the emergence of universality and the validity of the addition theorem for random matrices.
The algorithm by M.Bauer and O.Golinelli to evaluate the moments of the spectral density of the incident matrix of random graphs is very useful also for other matrix ensembles: real symmetric, real anti-symmetric, real, laplacian, Wishart,... In most cases it may efficiently be performed by computer. The moments thus evaluated presumably will be useful to complement numerical simulations. In the large n limit, they are a transparent way to examine possible n-dependent rescaling then the emergence of universality and the validity of the addition theorem for random matrices.
Posted by: brunel
Mon
13 Mar 2006
Adding branes to hyperkahler manifolds
Andrew Dancer
(Oxford)
Abstract:
We investigate quaternionic
(especially hyperkahler) analogues of the
symplectic cut construction. In low dimensions this can
be interpreted as a adding a brane to a hyperkahler manifold.
We investigate quaternionic
(especially hyperkahler) analogues of the
symplectic cut construction. In low dimensions this can
be interpreted as a adding a brane to a hyperkahler manifold.
Posted by: IC
Fri
10 Mar 2006
Perspectives in Mathematical and Theoretical Physics
Various speakers
(n/a)
Abstract:
Meeting of the IoP Mathematical and Theoretical Physics Group,
to be held at Imperial College on the 10th and 11th of March.
Registration requested. Details can be found here: http://groups.iop.org/MP/perspectives.html
Meeting of the IoP Mathematical and Theoretical Physics Group,
to be held at Imperial College on the 10th and 11th of March.
Registration requested. Details can be found here: http://groups.iop.org/MP/perspectives.html
Posted by: KCL
Thu
9 Mar 2006
M5-brane Geometry of Fermionic Open Strings
Neil Lambert
(KCL)
Thu
9 Mar 2006
Topological membranes on G2-manifolds
Maxim Zabzine
(HIS)
Abstract:
I will review the recent developments in topological membrane theory. In particular I will discuss the formulation of topological membrane theory on G2-manifolds and its role in the topological M-theory. The reduction to topological strings will be presented.
I will review the recent developments in topological membrane theory. In particular I will discuss the formulation of topological membrane theory on G2-manifolds and its role in the topological M-theory. The reduction to topological strings will be presented.
Posted by: IC
Thu
9 Mar 2006
The Soliton: Wave or Particle?
📍 London
Michael Atiyah
(University of Edinburgh)
Abstract:
Registration requested. For further details refer to
http://www.iee.org/events/kelvin.cfm
Registration requested. For further details refer to
http://www.iee.org/events/kelvin.cfm
Posted by: KCL
Wed
8 Mar 2006
Functional Bosonisation in Luttinger Liquid
Igor Lerner
(Birmingham)
Abstract:
We develop a functional integral formalism to find an exact representation for the electron Green function of the Luttinger liquid (LL) in the presence of a single backscattering impurity. This allows us to reproduce results (well known from the bosonization techniques) for the suppression of the electron local density of states (LDoS) at the position of the impurity and for the Friedel
oscillations at finite temperature. In addition, we have extracted from the exact representation an analytic dependence of LDoS on the distance from the impurity and shown how it crosses over to that for the pure LL.
We develop a functional integral formalism to find an exact representation for the electron Green function of the Luttinger liquid (LL) in the presence of a single backscattering impurity. This allows us to reproduce results (well known from the bosonization techniques) for the suppression of the electron local density of states (LDoS) at the position of the impurity and for the Friedel
oscillations at finite temperature. In addition, we have extracted from the exact representation an analytic dependence of LDoS on the distance from the impurity and shown how it crosses over to that for the pure LL.
Posted by: brunel
Wed
8 Mar 2006
Inflation in AdS - CFT
📍 London
Mukund Rangamani
(Durham)
Wed
8 Mar 2006
Identification of the stress-energy tensor in SLE and related processes
Valentina Riva
(Oxford)
Abstract:
In the first part of the talk, I will briefly review two complementary methods for the analytical study of two-dimensional critical phenomena: Conformal Field Theory (CFT) and Stochastic Loewner Evolution (SLE). I will then discuss some recent progress in understanding their connection, via the identification of some probabilities of SLE with correlation functions involving the bulk stress-energy tensor in CFT.
In the first part of the talk, I will briefly review two complementary methods for the analytical study of two-dimensional critical phenomena: Conformal Field Theory (CFT) and Stochastic Loewner Evolution (SLE). I will then discuss some recent progress in understanding their connection, via the identification of some probabilities of SLE with correlation functions involving the bulk stress-energy tensor in CFT.
Posted by: CityU
Tue
7 Mar 2006
tba
Johanna Erdmenger
(Max Planck Munich)
Mon
6 Mar 2006
Heterotic MSSM
Yang-Hui He
(Oxford)
Abstract:
We show the existence of an N=1 supersymmetric vacuum in
string theory whose observable sector has exactly the matter content of
the MSSM without exotic particles and vector-like pairs of any type. This
is done so by compactifying the E_8 x E_8 heterotic string on a
Calabi-Yau threefold endowed with an SU(4) vector bundle which has been
constructed after extensive search. In addition, we discuss the Yukawa
couplings
and Higgs mu-terms in this model.
We show the existence of an N=1 supersymmetric vacuum in
string theory whose observable sector has exactly the matter content of
the MSSM without exotic particles and vector-like pairs of any type. This
is done so by compactifying the E_8 x E_8 heterotic string on a
Calabi-Yau threefold endowed with an SU(4) vector bundle which has been
constructed after extensive search. In addition, we discuss the Yukawa
couplings
and Higgs mu-terms in this model.
Posted by: IC
Thu
2 Mar 2006
Fixing all moduli: Some Geometry
Susanne Reffert
(MPI Munich)
Abstract:
In the moduli stabilization program a la KKLT, the dilaton and the complex structure moduli are
fixed via background 3-form fluxes, whereas the Kaehler moduli are fixed through
non-perturbative effects such as Euclidean D3-brane instantons and gaugino condensation.
After briefly introducing toroidal orbifolds, I will discuss some issues of stability and then
turn to moduli stabilization in resolved toroidal type IIB orientifolds.
The main emphasis will be on the resolution of the singularities via blow-ups, gluing together
the local patches to obtain a smooth Calabi-Yau, and the topologies of the exceptional
divisors.
In the moduli stabilization program a la KKLT, the dilaton and the complex structure moduli are
fixed via background 3-form fluxes, whereas the Kaehler moduli are fixed through
non-perturbative effects such as Euclidean D3-brane instantons and gaugino condensation.
After briefly introducing toroidal orbifolds, I will discuss some issues of stability and then
turn to moduli stabilization in resolved toroidal type IIB orientifolds.
The main emphasis will be on the resolution of the singularities via blow-ups, gluing together
the local patches to obtain a smooth Calabi-Yau, and the topologies of the exceptional
divisors.
Posted by: IC
Wed
1 Mar 2006
On and around the Schur algebra
Anton Cox
(City U)
Abstract:
Due to the short notice of change of seminar there is currently not an abstract available.
Note: Peter West's seminar previously announced for this day has been postponed to next term.
Due to the short notice of change of seminar there is currently not an abstract available.
Note: Peter West's seminar previously announced for this day has been postponed to next term.
Posted by: CityU
Wed
1 Mar 2006
The classification of RCFTs
Terry Gannon
(Hamburg)
Abstract:
The classification of RCFT means different things to different people, but the most accessible, and perhaps the prettiest, aspect of it is the classification of modular invariant (torus) partition functions, which tell you the spectrum of the theory. I'll review the progress made recently on this problem, for the case where the chiral algebras come from affine Kac-Moody algebras (the so-called Wess-Zumino-Witten models). I'll also comment on the classification of cyclindrical partition functions (the
so-called NIM-reps), which are more directly relevant for the framework of Fuchs-Runkel-Schweigert.
The classification of RCFT means different things to different people, but the most accessible, and perhaps the prettiest, aspect of it is the classification of modular invariant (torus) partition functions, which tell you the spectrum of the theory. I'll review the progress made recently on this problem, for the case where the chiral algebras come from affine Kac-Moody algebras (the so-called Wess-Zumino-Witten models). I'll also comment on the classification of cyclindrical partition functions (the
so-called NIM-reps), which are more directly relevant for the framework of Fuchs-Runkel-Schweigert.
Posted by: KCL
Wed
1 Mar 2006
Aspects of Gauge - Strings Duality
Carlos Nunez
(Swansea)
Abstract:
I will discuss interesting aspects of the duality of gauge theories and string theories in new scenarios.
I will discuss interesting aspects of the duality of gauge theories and string theories in new scenarios.
Posted by: KCL
February 2006
Tue
28 Feb 2006
Large-N gauge theories : the view from the lattice
Mike Teper
(Oxford)
Abstract:
I review what one has learned about SU(N) gauge theories from lattice calculations. I will discuss the mass spectrum, finite T phase transitions, k-strings, topology and strong-to-weak coupling transitions as well as the basic question of how close N=3 is to N=infinity.
I review what one has learned about SU(N) gauge theories from lattice calculations. I will discuss the mass spectrum, finite T phase transitions, k-strings, topology and strong-to-weak coupling transitions as well as the basic question of how close N=3 is to N=infinity.
Posted by: IC
Mon
27 Feb 2006
Nongeometry, Duality Twists, and the Worldsheet
Brooke Williams
(Amsterdam)
Thu
23 Feb 2006
On T-folds and Supersymmetry
Emily Hackett-Jones
(Edinburgh)
Thu
23 Feb 2006
Stationary Spacetime from Intersecting M-branes
Makoto Tanabe
(Tokyo)
Abstract:
We study a stationary black brane in M-superstring theory. Assuming BPS-type relations between
the first-order derivatives of metric functions, we present general stationary black brane
solutions with a traveling wave for the Einstein equations in D-dimensions. The solutions are
given by a few independent harmonic equations (and plus the Poisson equation). General
solutions are constructed by superposition of a complete set of those harmonic functions. Using
the hyperspherical coordinate system for a conformally flat base space, we explicitly give the
solutions in 11-dimensional M-theory for the case with M2-M5 intersecting branes and a
traveling wave. Compactifying these solutions into five dimensions, we show that these
solutions include the BMPV black hole and the Brinkmann wave solution, and those extension to
non-BPS ones. We also find new solutions similar to the Brinkmann wave. We prove that the
solutions preserve the one eigth supersymmetry if the gravi-electromagnetic field, which is a
rotational part of gravity, is self-dual. We also discuss non-spherical black objects (e.g., a
ring topology and an elliptical shape) by use of other curvilinear coordinates.
We study a stationary black brane in M-superstring theory. Assuming BPS-type relations between
the first-order derivatives of metric functions, we present general stationary black brane
solutions with a traveling wave for the Einstein equations in D-dimensions. The solutions are
given by a few independent harmonic equations (and plus the Poisson equation). General
solutions are constructed by superposition of a complete set of those harmonic functions. Using
the hyperspherical coordinate system for a conformally flat base space, we explicitly give the
solutions in 11-dimensional M-theory for the case with M2-M5 intersecting branes and a
traveling wave. Compactifying these solutions into five dimensions, we show that these
solutions include the BMPV black hole and the Brinkmann wave solution, and those extension to
non-BPS ones. We also find new solutions similar to the Brinkmann wave. We prove that the
solutions preserve the one eigth supersymmetry if the gravi-electromagnetic field, which is a
rotational part of gravity, is self-dual. We also discuss non-spherical black objects (e.g., a
ring topology and an elliptical shape) by use of other curvilinear coordinates.
Posted by: IC
Wed
22 Feb 2006
Extremal single charge small black holes
📍 London
Aninda Sinha
(Cambridge)
Wed
22 Feb 2006
Spectral properties of quantum spin-chains of Temperley-Lieb type
Britta Aufgebauer
(Bergische Universitaet Wuppertal)
Abstract:
The abstract can be found at
http://www.city.ac.uk/sems/mathematics/seminars.html
The abstract can be found at
http://www.city.ac.uk/sems/mathematics/seminars.html
Posted by: CityU
Tue
21 Feb 2006
Collisions of Strings with Y Junctions
Tom Kibble
(Imperial College)
Abstract:
I will discuss the dynamics of Nambu–Goto strings with junctions at which three strings meet, in particular, the process of intercommuting of two straight strings, in which they exchange partners but become joined by a third string. I shall show that there are important kinematical constraints on this process. The exchange cannot occur if the strings meet with very large relative velocity. In the case of non-abelian strings, there is also a possibility that they can get locked, unable to separate in any direction. This may have important implications for the evolution of cosmic superstring networks and non-abelian string networks.
I will discuss the dynamics of Nambu–Goto strings with junctions at which three strings meet, in particular, the process of intercommuting of two straight strings, in which they exchange partners but become joined by a third string. I shall show that there are important kinematical constraints on this process. The exchange cannot occur if the strings meet with very large relative velocity. In the case of non-abelian strings, there is also a possibility that they can get locked, unable to separate in any direction. This may have important implications for the evolution of cosmic superstring networks and non-abelian string networks.
Posted by: IC
Mon
20 Feb 2006
tba
Dan Waldram
(Imperial)
Thu
16 Feb 2006
Brane collapse, quantum DBI and speed of light
Sanjaye Ramgoolam
(Queen Mary)
Abstract:
TBA
TBA
Posted by: IC
Thu
16 Feb 2006
Perturbative and Non-perturbative Results in the Beta-deformed N=4 SYM: from Amplitude Calculations to AdS-CFT
Valentin Khoze
(Durham)
Wed
15 Feb 2006
g-functions and boundaries, at and away from criticality
📍 London
Patrick Dorey
(Durham)
Mon
13 Feb 2006
Commuting involution graphs for various groups
Sarah Perkins
(Birkbeck)
Abstract:
tba
tba
Posted by: CityU
Fri
10 Feb 2006
Locality in quantum field theory
📍 London
Graeme Segal
(Oxford)
Abstract:
Mary Cartwright lecture of the London Mathematical Society.
Mary Cartwright lecture of the London Mathematical Society.
Posted by: KCL
Fri
10 Feb 2006
The topology of strings: Mumford's conjecture and beyond
📍 London
Ulrike Tillmann
(Oxford)
Abstract:
Mary Cartwright lecture of the London Mathematical Society.
Mary Cartwright lecture of the London Mathematical Society.
Posted by: KCL
Thu
9 Feb 2006
Supersymmetic nonlinear sigma model on noncommutative superspace
Takeo Inami
(Tokyo)
Abstract:
TBA
TBA
Posted by: IC
Thu
9 Feb 2006
CANCELED
Asad Naqvi
(Swansea)
Wed
8 Feb 2006
Cosmology and conifolds
📍 London
Paul Saffin
(Nottingham)
Abstract:
We shall discuss aspects of how internal manifolds evolve during cosmology, paying particular attention to the regions where the manifold changes topology.
We shall discuss aspects of how internal manifolds evolve during cosmology, paying particular attention to the regions where the manifold changes topology.
Posted by: KCL
Wed
8 Feb 2006
Representation theory, Q-operators and the Heisenberg spin-chain
Christian Korff
(City)
Abstract:
I will present an overview over work on the construction of Baxter's Q-operator. The latter is a an auxiliary tool in diagonalizing the Hamiltonian of integrable spin-chains. This is an alternative approach to the Bethe ansatz and has several advantages over the latter. I will highlight the representation theoretic construction of the Q-operator and discuss how this approach leads to a difference equation (called the quantum Wronskian) which is sufficient to determine the spectrum of the spin-chain Hamiltonian. In contrast to the Bethe ansatz equations which are of polynomial order (= number of sites of the chain) the quantum Wronskian leads to a system of quadratic equations. I will also briefly discuss how the Q-operator allows for an alternative description of the trace functional used in the recent discussion of correlation functions by Boos, Jimbo, Miwa, Smirnov and Takeyama.
I will present an overview over work on the construction of Baxter's Q-operator. The latter is a an auxiliary tool in diagonalizing the Hamiltonian of integrable spin-chains. This is an alternative approach to the Bethe ansatz and has several advantages over the latter. I will highlight the representation theoretic construction of the Q-operator and discuss how this approach leads to a difference equation (called the quantum Wronskian) which is sufficient to determine the spectrum of the spin-chain Hamiltonian. In contrast to the Bethe ansatz equations which are of polynomial order (= number of sites of the chain) the quantum Wronskian leads to a system of quadratic equations. I will also briefly discuss how the Q-operator allows for an alternative description of the trace functional used in the recent discussion of correlation functions by Boos, Jimbo, Miwa, Smirnov and Takeyama.
Posted by: CityU
Wed
8 Feb 2006
Noncommutative Geometry, Quantum Effects and DBI-scaling in the Collapse of D0-D2 Bound States
Nick Toumbas
(Cyprus)
Wed
8 Feb 2006
Random Planar Curves and Stochastic Loewner Evolution
John Cardy
(Oxford)
Abstract:
The random planar curves that occur, for example, as the boundaries of spin clusters in the Ising model or of percolation clusters in two dimensions have the special property of being conformally invariant in the scaling limit. I describe a new approach, called tochastic Loewner evolution (SLE), to describing the measure on such curves and to computing many of their properties.
The random planar curves that occur, for example, as the boundaries of spin clusters in the Ising model or of percolation clusters in two dimensions have the special property of being conformally invariant in the scaling limit. I describe a new approach, called tochastic Loewner evolution (SLE), to describing the measure on such curves and to computing many of their properties.
Posted by: brunel
Tue
7 Feb 2006
Entanglement in Harmonic Lattice Systems
Martin B. Plenio
(Imperial)
Abstract:
After a brief introduction to the basic concepts of
entanglement in discrete and continuous systems
I will outline various results of our recent work in these
areas. In particular, I will present a scaling relation
for the entanglement of a subsystem with respect
to the rest of the lattice in the size of the regions.
After a brief introduction to the basic concepts of
entanglement in discrete and continuous systems
I will outline various results of our recent work in these
areas. In particular, I will present a scaling relation
for the entanglement of a subsystem with respect
to the rest of the lattice in the size of the regions.
Posted by: IC
Mon
6 Feb 2006
M-theory Geometry of Fermionic Open Strings
Neil Lambert
(King's College)
Thu
2 Feb 2006
Area geometry and string backgrounds
Mattias Wohlfarth
(IFTP Hamburg)
Abstract:
Based on the observation that classical strings only couple to area, we study the generalized geometry of manifolds equipped with an area measure but not a metric length measure. This in particular includes geometries combined from a metric and a two-form. We discuss the equation of stationary surfaces on these backgrounds which leads to the identification of differential geometric structures appropriate for area geometry. This work is expected to be of relevance for the study of the gravitational sector of
strings and branes.
Based on the observation that classical strings only couple to area, we study the generalized geometry of manifolds equipped with an area measure but not a metric length measure. This in particular includes geometries combined from a metric and a two-form. We discuss the equation of stationary surfaces on these backgrounds which leads to the identification of differential geometric structures appropriate for area geometry. This work is expected to be of relevance for the study of the gravitational sector of
strings and branes.
Posted by: IC
Wed
1 Feb 2006
Black Hole Partition Functions and Duality
Thomas Mohaupt
(Liverpool)
Wed
1 Feb 2006
Brane world effective actions for D-branes with fluxes
📍 London
Rodolfo Russo
(Queen Mary)
Abstract:
I will discuss how to use string techniques to systematically
derive brane world effective actions for models with magnetized (or
equivalently intersecting) D-branes. In particular, I derive the
dependence on all NS-NS moduli of the kinetic terms of the chiral
matter in a generic non-supersymmetric brane configurations with
non-commuting open string fluxes. Near a N=1 supersymmetric point the
effective action contains D and F term breaking terms which can be
explicitly computed with string diagrams.
I will discuss how to use string techniques to systematically
derive brane world effective actions for models with magnetized (or
equivalently intersecting) D-branes. In particular, I derive the
dependence on all NS-NS moduli of the kinetic terms of the chiral
matter in a generic non-supersymmetric brane configurations with
non-commuting open string fluxes. Near a N=1 supersymmetric point the
effective action contains D and F term breaking terms which can be
explicitly computed with string diagrams.
Posted by: KCL
January 2006
Tue
31 Jan 2006
Supersymmetry and (generalised) Geometry
Dan Waldram
(Imperial)
Mon
30 Jan 2006
A new large N phase transition in two dimensional Yang-Mills theories
Sergio Arianos
(Turin University)
Abstract:
We review some correspondences between YM2 and the theory of random walks. In this spirit, we then consider YM2 in a non conventional large N limit, in which the coupling constant A is not fixed ('t Hooft scaling) but scales with a factor logN. In this regime the effective number of d.o.f. of the
model is proportional to N to the power k, with k(A) less than 2, rather than to N squared. Moreover, a transition corresponding to the cutoff transition in random walks occurs when k equal to zero. This transition may be thought of as a step further in the spirit of the Douglas-Kazakov transition.
We review some correspondences between YM2 and the theory of random walks. In this spirit, we then consider YM2 in a non conventional large N limit, in which the coupling constant A is not fixed ('t Hooft scaling) but scales with a factor logN. In this regime the effective number of d.o.f. of the
model is proportional to N to the power k, with k(A) less than 2, rather than to N squared. Moreover, a transition corresponding to the cutoff transition in random walks occurs when k equal to zero. This transition may be thought of as a step further in the spirit of the Douglas-Kazakov transition.
Posted by: brunel
Mon
30 Jan 2006
Twisted and generalized K3 surfaces
Daniel Huybrechts
(Bonn)
Wed
25 Jan 2006
Solving Strings on AdS-5 x S-5 in Truncated Sectors
📍 London
Gleb Arutyunov
(Utrecht)
Wed
25 Jan 2006
Explicit Invariant Measures for Products of Random Matrices
Lech Wolowski
(Bristol)
Abstract:
We construct a new family of invariant measures for
products of random matrices with gamma-distributed entries.
The invariant measures generalize the well know family of
GIG laws studied in the context of random continued fractions by Letac and Seshadri. The associated Lyapunov exponents are computed explicitly and the result is applied to the Anderson model with gamma-distributed potential yielding an explicit estimate on the localization rate.
We construct a new family of invariant measures for
products of random matrices with gamma-distributed entries.
The invariant measures generalize the well know family of
GIG laws studied in the context of random continued fractions by Letac and Seshadri. The associated Lyapunov exponents are computed explicitly and the result is applied to the Anderson model with gamma-distributed potential yielding an explicit estimate on the localization rate.
Posted by: brunel
Wed
25 Jan 2006
From Trees to Loops and Back
📍 London
Gabriele Travaglini
(QMW)
Tue
24 Jan 2006
Precision Dark Energy
Dragan Huterer
(Chicago)
Abstract:
Evidence for the existence of some form of dark energy – a smooth component that causes the accelerated expansion of the universe and contributes about 70 percent of the total energy density – is by now very solid. However, very little progress has been made in understanding its nature and the underlying physical mechanism. In this talk I describe the prospects of several promising methods to improve the measurements of dark energy properties within the next decade. In addition to type Ia supernovae, these include weak gravitational lensing, counts of clusters of galaxies, and cosmic microwave background anisotropies. I comment on specific upcoming surveys, and challenges in controlling the systematic errors so that these probes can achieve their full potential and help us understand the nature of dark energy.
Evidence for the existence of some form of dark energy – a smooth component that causes the accelerated expansion of the universe and contributes about 70 percent of the total energy density – is by now very solid. However, very little progress has been made in understanding its nature and the underlying physical mechanism. In this talk I describe the prospects of several promising methods to improve the measurements of dark energy properties within the next decade. In addition to type Ia supernovae, these include weak gravitational lensing, counts of clusters of galaxies, and cosmic microwave background anisotropies. I comment on specific upcoming surveys, and challenges in controlling the systematic errors so that these probes can achieve their full potential and help us understand the nature of dark energy.
Posted by: IC
Mon
23 Jan 2006
Picard-Lefschetz theory for holomorphic one-forms and complex symplectic geometry
Dietmar Salamon
(ETH Zurich)
Mon
23 Jan 2006
Finite groups with small automorphism group
Robert A. Wilson
(Queen Mary)
Abstract:
The abstract can be found at
http://www.city.ac.uk/sems/mathematics/seminars.html
The abstract can be found at
http://www.city.ac.uk/sems/mathematics/seminars.html
Posted by: CityU
Thu
19 Jan 2006
Matrix Representation of the Combinatorics of Renormalization in Perturbative QFT
Kurusch Ebrahimi-Fard
(IHES)
Abstract:
Kreimer discovered a Hopf algebra structure underlying the
combinatorics of renormalization in perturbative quantum field
theory. Later, Connes and Kreimer explored the link to
non-commutative geometry via a Hopf algebra of rooted trees and
described a Hopf algebra of Feynman graphs. After reviewing these
developments in some detail we show in this talk how to organize
the combinatorics of renormalization in terms of unipotent
triangular matrix representations. A simple decomposition of such
matrices is used to characterize the process of renormalization.
We thereby recover a matrix (anti-)representation of the Birkhoff
decomposition of Connes and Kreimer.
Kreimer discovered a Hopf algebra structure underlying the
combinatorics of renormalization in perturbative quantum field
theory. Later, Connes and Kreimer explored the link to
non-commutative geometry via a Hopf algebra of rooted trees and
described a Hopf algebra of Feynman graphs. After reviewing these
developments in some detail we show in this talk how to organize
the combinatorics of renormalization in terms of unipotent
triangular matrix representations. A simple decomposition of such
matrices is used to characterize the process of renormalization.
We thereby recover a matrix (anti-)representation of the Birkhoff
decomposition of Connes and Kreimer.
Posted by: QMW
Thu
19 Jan 2006
Mass Corrections to KK-states in Dipole Field Theories
Karl Landsteiner
(UAM)
Wed
18 Jan 2006
Sigma models on supermanifolds: Integrability and Conformal Invariance
📍 London
Charles Young
(York)
Thu
12 Jan 2006
The Origin of String Perturbation Theory from M-theory
David Berman
(QMW)
Wed
11 Jan 2006
Moduli Stabilization in Heterotic Flux Compactifications
📍 London
Andre Lukas
(Oxford)