Please note that this is an evolving programme. It is advisable to (reload and) recheck the page shortly before each talk. There is a mailing list for the seminar announcements. For further details please contact Eli Hawkins.
Past Seminars
Past Mathematical Physics Seminars 19992007
See the navigation menu on the lefthand side.
Summer 2007
The seminar takes place on Mondays and Thursdays: from 4:20 pm onwards in the very relaxed atmosphere of Room G/109 in Goodricke College. The seminars are preceded by tea from 4 pm. The typical length of the talks is about 1 hour.
 Monday, 30 April 2007, 04:20 PM » 05:20 PM
Title: Gribov copies and confinement
Speaker: Antony Ilderton (University of Plymouth)
Room: G/109
Abstract: I will present an elegant and explicit construction of a wide class of Gribov copies. Although they may be generated infinitesimally, the copies are manifestly nonperturbative. As a consequence it will be demonstrated that the existence of copies provides a nonperturbative justification for the absence of physical coloured charges.  Monday, 14 May 2007, 04:20 PM » 05:20 PM
Title: Almost quantum theory: classical theories with a constraint on knowledge
Speaker: Robert W. Spekkens (DAMTP, Cambridge)
Room: G/109
Abstract: What kind of theory would be appropriate for an agent living in a world that is essentially classical but where there is a fundamental restriction on how much knowledge can be acquired about the physical state of any system? Formalizing such a restriction, one can define several toy theories that are found to have a rich structure similar to that of quantum theory, including a notion of coherent superposition and entanglement. These theories are also found to have analogues of a wide variety of quantum phenomena, such as complementarity, interference, teleportation, nocloning, and many quantum cryptographic and communication protocols. The diversity and quality of these analogies provides compelling evidence for the view that quantum states are not states of reality  as most interpretations suggest  but rather states of knowledge that are incomplete (and cannot be completed). The question "what is the nature of the reality to which this knowledge refers?" remains open in this research program but the phenomenon of contextuality (a consequence of the BellKochenSpecker theorem) provides, I argue, our best clue for how to answer it.  Thursday, 24 May 2007, 04:20 PM » 05:20 PM
Title: A New Approach to the Quantum Measurement Problem
Speaker: Geoffrey Sewell (Queen Mary)
Room: G/109
Abstract: The question I shall address is the highly contentious one of whether the traditional form of quantum mechanics, as represented by Schroedinger dynamics and the probabilistic interpretation thereof, covers the measurement process. The problem that arises here is that, whereas the Schroedinger evolution of a system is unitary, its change of state in the measurement process is highly nonunitary (cf. Von Neumann). My treatment of this problem is based on an analysis of the Schroedinger dynamics of the generic conservative model comprising an observed microsystem S and a macroscopic measuring instrument M, whose pointer positions correspond to values of a set of intercommuting macroscopic observables. My main result is that, for a suitable choice of these latter obsrvables and a suitable SM coupling, the dynamics of the composite (S+M) induces both the change of state of S and the registartion of that change by M demanded by Von Neumann's phenomenological theory of the measurement process. Thus I conclude that the traditional picture of quantum mechanics is complete, in that that the measurement theory does indeed ensue from Schroedinger dynamics together with Born's probabilistic interpretation thereof.  Thursday, 31 May 2007, 04:20 PM » 05:20 PM
Title: On defects in classical integrable systems
Speaker: Vincent Caudrelier (York)
Room: G/109
Abstract: This talk will be largely introductory. The basic idea is to propose a reformulation of the lagrangian formalism, already presented by Ed Corrigan and Peter Bowcock in previous seminars, to the question of integrable defects in field theories in 1+1 dimensions. This reformulation uses a very nice observation systematically made on a case by case basis in their work: a large class of internal (defect) boundary conditions preserving integrability is realised as Bäcklund transformations frozen at the point of the defect. I will review all these things (so everybody is welcome) and show how this can be recast in the efficient language of inverse scattering method, which will be introduced as well. Despite a possibly less appealing formalism (depending on your tastes), this approach has a number of advantages which I will present: unified proof of integrability for a large class of systems, explicit generating function of the integrals of motion, classification of defect conditions and finally, a possible way towards quantization. I will not talk about solitons, this topic having already been substantially covered by Ed and Peter.
 Thursday, 7 June 2007, 04:20 PM » 05:20 PM
Title: Poisson structures associated with the Schrödinger equation
Speaker: Ian Marshall
Room: G/109
Abstract: I shall present a new and surprisingly simple Poisson piece of the Schrödinger / KdV correspondence. It gives rise to a PoissonLie group of symmetries acting naturally on the space of wave functions.  Monday, 11 June 2007, 04:20 PM » 05:20 PM
Title: Quasihermitian Liouville Theory
Speaker: Thomas Curtright (University of Miami)
Room: G/109
Abstract: I will briefly discuss properties of quasihermitian (PTsymmetric) theories in the context of a simple exactly solvable example, "imaginary" Liouville theory. I will use a deformation quantization approach, i.e. QM in phase space. Then I will discuss the field theory extension of this model, of interest in string theory.  Monday, 18 June 2007, 04:20 PM » 05:20 PM
Title: Expectation values for thermal states on lukewarm black holes
Speaker: Elizabeth Winstanley (University of Sheffield)
Room: G/109
Abstract: It is wellknown that no regular "HartleHawking"like state can exist on Schwarzschildde Sitter black holes, where the event and cosmological horizons are of different temperatures. However, for a ReissnerNordstromde Sitter black hole where the two horizons have the same temperature ("lukewarm" black holes) then we may construct a regular thermal state at this temperature. We report on calculations of the renormalized expectation values of $\phi^2$ and $T_{\mu \nu}$ for this thermal state on a lukewarm black hole background. We follow the method of Anderson, Hiscock and Samuel, which will be reviewed in detail.
 Tuesday, 26 June 2007, 04:30 PM » 05:30 PM
Title: Enhanced black hole horizon fluctuations
Speaker: Larry Ford (Tufts University)
Room: G/020  Thursday, 28 June 2007, 04:20 PM » 05:20 PM
Title: Quantum spectral curves, quantum integrable systems and the geometric Langlands correspondence. Lecture 1
Speaker: Alexander Chervov (Institute for Theoretical and Experimental Physics, Moscow)
Room: G/109
Abstract: The spectral curve is the key ingredient in the modern theory of classical integrable systems. We develop a construction of the "quantum spectral curve" and argue that it takes the analogous structural and unifying role on the quantum level also. In the simplest, but essential case the "quantum spectral curve" is given by the formula "det"$(L(z)\partial_z)$ [Talalaev04] (hepth/0404153). As an easy application of our constructions we obtain the following: quite a universal receipt to define quantum commuting hamiltonians from the classical ones, in particular an explicit description of a maximal commutative subalgebra in $U({\bf{gl}}_n[t])/t^N$ and in $U({\bf{gl}}_n[t^{1}]) \otimes U(t\, {\bf{gl}}_n[t])$; its relation with the center on the of the affine algebra; an explicit formula for the center generators and a conjecture on Walgebra generators; a receipt to obtain the qdeformation of these results; the simple and explicit construction of the Langlands correspondence; the relation between the "quantum spectral curve" and the KnizhnikZamolodchikov equation; new generalizations of the KZequation; the conjecture on rationality of the solutions of the KZequation for special values of level. In the simplest cases we observe the coincidence of the "quantum spectral curve" and the socalled Baxter equation. Connection with the KZequation offers a new powerful way to construct the Baxter's Qoperator.
Based on hepth/0604128 (authors: A. Chervov, D. Talalaev).  Monday, 9 July 2007, 04:20 PM » 05:20 PM
Title: Quantum spectral curves, quantum integrable systems and the geometric Langlands correspondence. Lecture 2
Speaker: Alexander Chervov (Institute for Theoretical and Experimental Physics, Moscow)
Room: G/109
Abstract: The spectral curve is the key ingredient in the modern theory of classical integrable systems. We develop a construction of the "quantum spectral curve" and argue that it takes the analogous structural and unifying role on the quantum level also. In the simplest, but essential case the "quantum spectral curve" is given by the formula "det"$(L(z)\partial_z)$ [Talalaev04] (hepth/0404153). As an easy application of our constructions we obtain the following: quite a universal receipt to define quantum commuting hamiltonians from the classical ones, in particular an explicit description of a maximal commutative subalgebra in $U({\bf{gl}}_n[t])/t^N$ and in $U({\bf{gl}}_n[t^{1}]) \otimes U(t\, {\bf{gl}}_n[t])$; its relation with the center on the of the affine algebra; an explicit formula for the center generators and a conjecture on Walgebra generators; a receipt to obtain the qdeformation of these results; the simple and explicit construction of the Langlands correspondence; the relation between the "quantum spectral curve" and the KnizhnikZamolodchikov equation; new generalizations of the KZequation; the conjecture on rationality of the solutions of the KZequation for special values of level. In the simplest cases we observe the coincidence of the "quantum spectral curve" and the socalled Baxter equation. Connection with the KZequation offers a new powerful way to construct the Baxter's Qoperator.
Based on hepth/0604128 (authors: A. Chervov, D. Talalaev).  Thursday, 12 July 2007, 04:20 PM » 05:20 PM
Title: Quantum spectral curves, quantum integrable systems and the geometric Langlands correspondence. Lecture 3
Speaker: Alexander Chervov (Institute for Theoretical and Experimental Physics, Moscow)
Room: G/109
Abstract: The spectral curve is the key ingredient in the modern theory of classical integrable systems. We develop a construction of the "quantum spectral curve" and argue that it takes the analogous structural and unifying role on the quantum level also. In the simplest, but essential case the "quantum spectral curve" is given by the formula "det"$(L(z)\partial_z)$ [Talalaev04] (hepth/0404153). As an easy application of our constructions we obtain the following: quite a universal receipt to define quantum commuting hamiltonians from the classical ones, in particular an explicit description of a maximal commutative subalgebra in $U({\bf{gl}}_n[t])/t^N$ and in $U({\bf{gl}}_n[t^{1}]) \otimes U(t\, {\bf{gl}}_n[t])$; its relation with the center on the of the affine algebra; an explicit formula for the center generators and a conjecture on Walgebra generators; a receipt to obtain the qdeformation of these results; the simple and explicit construction of the Langlands correspondence; the relation between the "quantum spectral curve" and the KnizhnikZamolodchikov equation; new generalizations of the KZequation; the conjecture on rationality of the solutions of the KZequation for special values of level. In the simplest cases we observe the coincidence of the "quantum spectral curve" and the socalled Baxter equation. Connection with the KZequation offers a new powerful way to construct the Baxter's Qoperator.
Based on hepth/0604128 (authors: A. Chervov, D. Talalaev).  Thursday, 19 July 2007, 02:00 PM » 03:00 PM
Title: "Low Energy Quantum Gravity" workshop
All lectures will take place in B/B006 (Biology). The provisional program is below. For more details, see http://winstanley.staff.shef.ac.uk/LEQG.html
All are welcome to attend, but if you plan to attend, please send an email to leqg.york@googlemail.com
Programme:
LowEnergy Quantum Gravity,
University of York, 19th20th July 2007, Biology Lecture Theatre B/B006
Thursday 19th July
2.00  3.15 pm David Toms (Newcastle)
Quantum gravity and gauge coupling constants
3.15  3.45 pm Tea and coffee
3.45  4.25 pm Calvin Smith (Dublin)
Bounds on negative energy in quantum field theory
4.25  4.55 pm Jorma Louko (Nottingham)
How often does an accelerated particle detector click?
4.55  5.35 pm Jean Alexandre (KCL)
A nonperturbative timedependent string configuration without extra dimensions?
Friday 20th July
9.30  10.45 am KarlHenning Rehren (Gottingen)
AdSCFT correspondence and CFT with boundaries
10.45  11.15 am Tea and coffee
11.15 am  12.30 pm Remo Garattini (Bergamo)
A multi gravity approach to spacetime foam
12.30  2.00 pm Lunch
2.00  2.40 pm Veronika Hubeny (Durham)
Emergence of spacetime in AdS/CFT
2.40  3.20 pm Atsushi Higuchi (York)
Infrared properties of quantum field theories in de Sitter spacetime
3.20 pm Tea and coffee
 Thursday, 26 July 2007, 04:20 PM » 05:05 PM
Title: Clustering and caustics in turbulent aerosols
Speaker: Michael Wilkinson (The Open University)
Room: G/109
Abstract:
Small particles suspended in a turbulent gas can cluster together. It is widely believed that this is due to particles being ‘centrifuged’ away from vortices. It has also been proposed that this clustering effect results in an increased rate of collision of particles.
I will describe recent results which quantify the clustering of particles, by means of a mapping to a perturbation of a ninedimensional quantum harmonic oscillator. The centrifugal effect plays no role in my model, and the results are in good agreement with simulations of particles in turbulent flows.
I also argue that the increased rate of collision of particles in turbulent flows is primarily caused by the generation of caustics in the velocity field of the particles, rather than spatial clustering.
These results are relevant to the initiation of rainfall from cumulus clouds, or the formation of planets from dust around a young star.
Spring 2007
The seminar takes place on Mondays and Thursdays: from 4:20 pm onwards in the very relaxed atmosphere of Room G/109 in Goodricke College. The seminars are preceded by tea from 4 pm. The typical length of the talks is about 1 hour.
 Monday, 15 January 2007, 04:20 PM » 05:20 PM
Title: Integrability and the AdS/CFT Correspondence
Speaker: Nick Dorey (DAMTP, Cambridge)
Room: G/109
Abstract: I will discuss the emergence of integrability in planar $N=4$ SUSY YangMills and in the dual string theory on $AdS_{5} \times S^{5}$. I will also review recent progress in exploiting integrability to determine the exact spectrum.  Thursday, 18 January 2007, 04:20 PM » 05:20 PM
Title: Spinor vector duality in fermionic $\mathbb{Z}_2 \times \mathbb{Z}_2$ heteroticstring orbifolds
Speaker: Alon Faraggi (University of Liverpool)
Room: G/109  Monday, 22 January 2007, 04:20 PM » 05:20 PM
Title: Integrable systems, analytic difference equations, special functions, Hilbert space: On the crossroads
Speaker: Simon Ruijsenaars (Loughborough)
Room: G/109
Abstract: In this lecture we aim to survey the 4 areas mentioned above, with a bias towards the study of special classes of analytic difference operators. The problem of understanding their Hilbert space features centers around the issue of orthogonality and completeness of suitable eigenfunction transforms, which generalize various previously known transforms (the most wellknown being Fourier transformation). The analytic difference operators arise from certain integrable systems, including nonlocal soliton equations and relativistic Nparticle systems of CalogeroMoser and Toda type.  Monday, 29 January 2007, 04:20 PM » 05:20 PM
Title: Reflection equation and twisted Yangians
Speaker: Andrey Mudrov (York)
Room: G/109
Abstract: With any involutive antialgebra and coalgebra automorphism of a quasitriangular bialgebra we associate a reflection equation algebra. A Hopf algebraic treatment of the reflection equation of this type and its universal solution is given. Applications to the twisted Yangians are considered.  Monday, 5 February 2007, 04:20 PM » 05:20 PM
Title: Black holes, qubits and the Fano Plane
Speaker: Michael Duff (Imperial College)
Room: G/109
Abstract: We review some recently established connections between the mathematics of black hole entropy in string theory and that of multipartite entanglement in quantum information theory. In the case of $N=2$ black holes and the entanglement of three qubits, the quartic $[SL(2)]^3$ invariant, Cayley's hyperdeterminant, provides both the black hole entropy and the measure of tripartite entanglement. In the case of $N=8$ black holes and the entanglement of seven qubits, the quartic $E_{7}$ invariant of Cartan provides both the black hole entropy and the measure of a particular tripartite entanglement encoded in the Fano plane.  Monday, 12 February 2007, 04:20 PM » 05:20 PM
Title: Irreducibility of fusion modules over twisted Yangians at generic point
Speaker: Andrey Mudrov (York)
Room: G/109
Abstract: With any skew Young diagram one can associate a one parameter family of "elementary" modules over the Yangian $Y(gl_N)$. Consider the twisted Yangian $Y(g_N)$, a subalgebra in $Y(gl_N)$, associated with a classical matrix Lie subalgebra $g_N$ in $gl_N$. Regard the tensor product of elementary Yangian modules as multiparameter family of modules over $Y(g_N)$ by restriction. We prove irreducibility of such modules for generic values of the parameters.  Monday, 19 February 2007, 04:15 PM » 05:15 PM
Title: Spin Foam models for quantum gravity
Speaker: John Barrett (Nottingham)
Room: G/109  Thursday, 22 February 2007, 04:20 PM » 05:20 PM
Title: The $P(\Phi)_2$ model on the de Sitter space
Speaker: Christian Jaekel (University of Talca, Chile)
Room: G/109
This is joined work with J. Barata and J. Mund.
Abstract: We provide a selfcontained construction of the model, based on a great variety of methods and results from the literature, including harmonic analysis on symmetric spaces, group representation theory, Markov processes, TomitaTakesaki modular theory and OsterwalderSchrader reconstruction theorems. The thermal aspects (Hawking temperature) induced by the curvature and the exceptional case of particles with small masses are discussed in the interacting case. We also explore the relations of the euclidean approach to the Wightman and HaagKastler axiomatic schemes which have been proposed for de Sitter space recently.  Monday, 5 March 2007, 04:20 PM » 05:20 PM
Title: Vacuum Energy Density of a Quantized Scalar Field
Speaker: Stephen A. Fulling (Texas A&M University)
Room: G/109
Abstract: The energy density (as distinct from total energy) involves interesting mathematics and controversial physics. Regularization by an ultraviolet cutoff leads to reformulation of the problem in terms of "cylinder kernels" (Green functions of elliptic boundary value problems with an extra dimension), which can be related to heat and resolvent kernels, zeta functions, and local densities of states, but yield vacuum energies more directly. The signs of vacuum energies are related to the phases of oscillations in the eigenvalue density indexed by periodic orbits; for densities the relevant classical paths are closed but not necessarily periodic. The energy density generally is divergent as a boundary is approached, and therefore the naively renormalized total energy is not equal to the spatial integral of the renormalized density. This raises the issue of consistency of the theory with general relativity, as well as that of physical validity of calculations of Casimir forces other than those between rigid bodies. When the integration is done before the cutoff is removed, some of these divergences (notably those at corners) disappear. For the others we argue that the traditional renormalization philosophy is applicable: In the absence of a detailed microscopic model of the boundary material (playing the same role as unknown ultrahighenergy physics), formally infinite terms should be replaced by finite terms with the same geometrical form and unknown coefficients that must be fixed experimentally. In particular, a consistent interpretation of the Einstein equation with distributional sources is being developed in collaboration with Ricardo Estrada, Kim Milton, Klaus Kirsten, and Lev Kaplan.  Monday, 12 March 2007, 04:20 PM » 05:20 PM
Title: New methods in the study of nonequilibrium impurity systems: the interacting resonant level model
Speaker: Benjamin Doyon (Oxford)
Room: G/109
Abstract: With the example of the interacting resonant level model (IRLM), we show how to fully exploit simple properties of HershfieldÃ¢â‚¬â„¢s Y operator along with Ã¢â‚¬Å“impurity conditionsÃ¢â‚¬Â in impurity models in order to obtain perturbative expansions of quantum averages in any steady state. In nonequilibrium steady states, this offers a powerful alternative to SchwingerKeldysh realtime perturbation theory or LippmannSchwinger scattering state formulation. We show how to solve the combinatorics of perturbative treatments, giving all integrals of the expansion without the use of Feynman diagrams. We also point out in this context how perturbation theory is connected to exact techniques based on Bethe ansatz. In the nonequilibrium IRLM, we obtain all integrals involved in the full perturbative expansion of the current in the Coulomb coupling U. Using renormalisationgroup improvement, we obtain the current to first order in U for all values of voltage and temperature.  Monday, 7 May 2007, 04:20 PM » 05:20 PM
Title: TBA
Speaker: Robert W. Spekkens (DAMTP, Cambridge)
Room: G/109
Please note that this is the tentative evolving program. It is advisable to (reload and) recheck the page shortly before each talk. There is a mailing list for the seminar announcements. For further details please contact Boris Noyvert.
Autumn 2006
The seminar takes place on Mondays and Thursdays: from 4:20 pm onwards in the very relaxed atmosphere of Room G/109 in Goodricke College. The seminars are preceded by tea from 4 pm. The typical length of the talks is about 1 hour.
 Monday, 9 October 2006, 04:20 PM » 05:20 PM
Title: Classical and Quantum Radiation Reaction
Speaker: Atsushi Higuchi (University of York)
Room: G/109
Abstract: In classical electrodynamics the selfforce on a charged point particle due to its own electromagnetic radiation is described by the LorentzDirac force. We show that this force can be derived by taking the classical limit of the lowestorder perturbation theory in quantum electrodynamics. (This work was done in collaboration with Giles Martin.)  Thursday, 19 October 2006, 04:20 PM » 05:20 PM
Title: CFT description of black holes
Speaker: Mukund Rangamani (Durham University)
Room: G/109  Monday, 30 October 2006, 04:20 PM » 05:20 PM
Title: Integrable defects
Speaker: Ed Corrigan (University of York)
Room: G/109  Monday, 6 November 2006, 04:20 PM » 05:20 PM
Title: Form factors of XXX and XXZ mixed finite spin chains
Speaker: Olalla CastroAlvaredo (City University London)
Room: G/109
Abstract: In this talk I will present new formulae for the form factors of the generators of the su(2) algebra associated to XXX quantum spin chains. The main novelty is that these formulae hold for generic spin representations of the operators considered, as well as for generic spin representations at the remaining sites of the chain. Therefore they can be specialized to a number of physically interesting cases such as alternating chains or spin chains with impurities. These expressions have been obtained by employing the approach developed by the group of the ENSLyon around J.M. Maillet.
In addition, if I have enough time I will briefly describe how the socalled inverse scattering problem for the su(2)q spin generators characterizing the symmetry of quantum XXZ spin chains can be solved for generic spin representations.
 Thursday, 16 November 2006, 04:20 PM » 05:20 PM
Title: Defect lines in conformal field theory
Speaker: Ingo Runkel (King's College)
Room: G/109
Abstract: Just like one can define conformal boundary conditions for a two dimensional CFT, it is possible to join two CFTs along a conformally invariant "seam" or defect line. For such defects one can introduce reflection and transmission coefficients, defined via the stress tensors of the CFTs. Of particular interest are fully transmitting defects, because they contain information about symmetries and about orderdisorder dualities of the CFT.  Thursday, 23 November 2006, 04:20 PM » 05:20 PM
Title: Exact perturbation theory for Jacobi matrices
Speaker: Evgeny Sklyanin (University of York)
Room: G/109
Abstract: We report of the recent progress in developing an exact perturbative expansion for the spectrum and eigenvectors of tridiagonal (Jacobi) matrices. We present a new method of derivation of a multivariate hypergeometric representation for the series based on the multidimensional residue theory. A generalization to multiparameter spectral problem as well as possible applications to exactly solvable models (Bethe Ansatz) are discussed.  Thursday, 30 November 2006, 04:20 PM » 05:20 PM
Title: Dynamical defects
Speaker: Peter Bowcock (Durham)
Room: G/109  Thursday, 7 December 2006, 04:20 PM » 05:20 PM
Title: Associahedra and Integrable Models
Speaker: Charles Young (Durham university)
Room: G/109
Abstract: As part of some work in progress, Nicolas Crampe and I have found ourselves looking at interesting geometrical objects known as the "permutohedra", "associahedra", and even "permutoassociahedra". I will try to explain what these are and how they are related to integrable models and quantum groups.
Autumn 2005
The seminar takes place on Mondays and Thursdays: from 4:20 pm onwards in the very relaxed atmosphere of Room G/109 in Goodricke College. The seminars are preceded by tea from 4 pm. The typical length of the talks is about 1 hour. Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Charles Young by email if you need further information. Please also check the Departmental Events Calendar for other seminars which might be of interest. For example the Departmental Colloquium talks on Wednesdays sometimes are on mathematical physics. ProgrammePlease note that this is the tentative evolving program. It is advisable to (reload and) recheck the page shortly before each talk. There is a mailing list for the seminar announcements. For further details please contact Charles Young 

20th October 2005 Thursday 4.20pm  David Kagan (DAMTP, Cambridge) Supersymmetric Quantum Mechanics: Central Extensions and Extra Dimensions


24th October 2005 Monday 4.20pm  Masashi Hamanaka (Nagoya University) Towards Noncommutative Integrable Systems and Soliton Theories


27th October 2005 Thursday 4.20pm  Thomas Quella (Kings College, London) Supergroup sigmamodels and strings in RR backgrounds


31st October 2005 Monday 4.20pm  Mathematical Physics Group Meeting


3rd November 2005 Thursday 4.20pm  Calvin Smith (York) TBA


7th November 2005 Monday 4.20pm  Bernard Kay (York) Quantum Field Theory in Curved Spacetime


10th November 2005 Thursday 4.20pm  Terry Rudolph (Imperial) How good must single photon sources be for optical quantum computation?› + Loss tolerant cluster state computation›


14th November 2005 Monday 4.20pm 


17th November 2005 Thursday 4.20pm  David Olive (Swansea) Minimal representations and Freudenthal Triple Systems


21st November 2005 Monday 4.20pm 

24th November 2005 Thursday 4.20pm  Valentina Riva (Oxford) New perspective on critical phenomena: SLE and its connection with CFT.


28th November 2005 Monday 4.20pm  Ruth Williams (DAMTP, Cambridge) Discrete Quantum Gravity


1st December 2005 Thursday 4.20pm  Gaetano Bertoldi (Swansea) Large N doublescaling limits of 4d gauge theories


5th December 2005 Monday 4.20pm 


8th December 2005 Thursday 4.20pm  Jonathan Halliwell (Imperial) Emergent Classicality via Commuting Position and Momentum Operators


12th December 2005 Monday 4.20pm 


15th December 2005 Thursday 4.20pm  Lutz Osterbrink (York) Energy inequalities for the nonminimally coupled scalar field 

19th December 2005 Monday 4.20pm  Yann Golanski (York) Dark energy: Who would have thought Einstein was right?


See also our Archive of Past Mathematical Physics Seminars
Summer 2005
Mathematical Physics Seminars
Summer 2005
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room G/109 in Goodricke College. The seminars are preceded by
tea from 4 pm. The typical length of the talks is about
1 hour.
Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Bernard Kay by email if you need further information.
Programme
Please note that this is the tentative evolving program. It is advisable to (reload and) recheck the page shortly before each talk. There is a
mailing list for the seminar announcements. For further details please contact
Bernard Kay
Spring 2005
Mathematical Physics Seminars
Spring 2005
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room G/109 in Goodricke College. The seminars are preceded by
tea from 4 pm. The typical length of the talks is about
1 hour.
Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Bernard Kay by email if you need further information.
Please also check the Departmental Events Calendar for other seminars which might be of interest. For example the Departmental Colloquium talks on Wednesdays sometimes are on mathematical physics.
Programme
Please note that this is the tentative evolving program. It is advisable to (reload and) recheck the page shortly before each talk. There is a
mailing list for the seminar announcements. For further details please contact
Bernard Kay
17th January 2005 Monday 4.20pm  Vincent Caudrelier (LAPTH, Annecy) Impurity in integrable systems: tools, examples and physical consequences 
20th January 2005 Thursday 4.20pm  Andrei Mudrov (MPI, Bonn) Explicit equivariant quantization of semisimple conjugacy classes of simple matrix groups 
27th January 2005 Thursday 4.20pm  Nicola Pinamonti (Trento, Italy) Conformal symmetry breaking on Killing horizons 
31st January 2005 Monday 4.20pm  Jorma Louko (Nottingham) Spin and charges: Weapons of mass construction 
10th February 2005 Thursday 4.20pm  Zoltan Nagy (CergyPontoise) Construction of commuting traces and spin chains using dynamical quadratic algebras 
17th February 2005 Thursday 4.20pm  Matthias Christandl (CQG, Cambridge) Uncertainty, monogamy, and implications for entanglement 
21st February 2005 Monday 4.20pm  Ian Hinder (Southampton) Stability in numerical relativity 
24th February 2005 Thursday 4.20pm  Nilanjana Datta (CQG, Cambridge) Perfect state transfer in quantum spin networks 
28th February 2005 Monday 4.20pm  Jie Xiao (Tsinghua University, Beijing) Quiver representations, RingelHall algebras and quantum groups 
7th March 2005 Monday 4.20pm  Graeme Mitchison (CQG, Cambridge) The spectra of quantum states and their marginals: a group representation perspective 
10th March 2005 Thursday 4.20pm  Veronique Hussin (CRM, Montreal) Degeneracies of the energy spectrum of the JaynesCummings model and coherent states 
14th March 2005 Monday 4.20pm  Valentina Riva (Oxford) Semiclassical methods in 2D QFT: spectra and finitesize effects 
PhysicsHinderabstract2005
Abstract of Talk Stability in Numerical Relativity
by Ian Hinder (Southampton)
When solving the Einstein equations numerically, much emphasis is placed on the stability of the numerical scheme. For formulations of the time evolution equations which are second order in space, special care has to be taken in the definition of stability. I review our recent work in this area, as well as notions of wellposedness for the associated second order in space PDE systems.
PhysicsMitchisonabstract2005
Abstract of Talk The spectra of quantum states and their marginals: a group representation perspective.
by Graeme Mitchison (CQG, Cambridge)
I shall describe joint work with Matthias Christandl in which we investigated the "quantum marginal problem". Imagine that one is given a bipartite quantum state (a density matrix rho_AB). By tracing out each party, one obtains two marginal states (density matrices rho_A and rho_B). The spectra of the original state and its two marginals consitute a special triple, and we found a way to characterize such triples in terms of representations of the symmetric group.
PhysicsNagyabstract2005
Abstract of Talk Construction of commuting traces and spin chains using dynamical quadratic algebras.
by Zoltan Nagy (CergyPointoise)
I will talk about dynamical extensions of quadratic quantum exchange algebras introduced by Freidel and Maillet and discuss their fusion and comodule structures. I will then show how these structures allow for building of commuting traces and spin chain type hamiltonians.
Autumn 2004
Mathematical Physics Seminars
Autumn 2004
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room G/109 in Goodricke College. The seminars are preceded by
tea from 4 pm. The typical length of the talks is about
1 hour.
Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Bernard Kay by email if you need further information.
Please also check the Departmental Events Calendar for other seminars which might be of interest. For example the Departmental Colloquium talks on Wednesdays sometimes are on mathematical physics.
Programme
Please note that this is the tentative evolving program. It is advisable to (reload and) recheck the page shortly before each talk. There is a
mailing list for the seminar announcements. For further details please contact
Bernard Kay
18th October Monday 4.20pm  Mathematical Physics Group Meeting 
25th October Monday 4.20pm  Martin Speight (Leeds) Algebraic topology of the Skyrme configuration space 
28th October Thursday 4.20pm  Minitalks by Atsushi Higuchi, Barry Miller and Charles Young (York) 
1st November Monday 4.20pm  Minitalks by Calvin Smith, Giles Martin, and Varqa Abyaneh (York) 
11th November Thursday 4.20pm  Simon Ross (Durham) Timedependent spacetimes in AdS/CFT 
15th November Monday 4.20pm  Nick Evans (Southampton) A gravitational dual description of chiral symmetry breaking 
22nd November Monday 4.20pm  Roberto Casadio (Bologna) Improved WKB analysis of cosmological perturbations 
25 November Thursday 4.20pm  Richard Szabo (Heriot Watt) 2D YangMills theory and moduli spaces of holomorphic differentials 
2nd December Thursday 4.20pm  Nicolas Crampe' (York) Closed and open spin chain in any representation 
6th December Monday 4.20pm  Ron King (Southampton) Local equivalence of twoqubit states: a problem in invariant theory 
13th December Monday 4.20pm  Robert Weston (Heriot Watt) Transmitting defects in solvable lattice models 
PhysicsCasadioabstract2004
Abstract of Talk Improved WKB analysis of cosmological perturbations
by Roberto Casadio (Bologna)
I present improved WKBtype approximations in order to study cosmological perturbations beyond the lowest order. The methods are based on functions which approximate the true perturbation modes over the complete range of the independent variable, including the turning point, and employ both a perturbative Green's function technique and an adiabatic expansion in order to compute higher order corrections. The methods are tested on the benchmark of powerlaw inflation: the nexttoleading order adiabatic expansion yields the amplitude of the power spectra with excellent accuracy, whereas the nexttoleading order with the perturbative Green's function method does not improve the leading order result significantly. In more general cases, either or both methods may be useful.
PhysicsKingabstract2004
Abstract of Talk
Local equivalence of twoqubit states: a problem in invariant theory
by Ron King (Southampton)
Twoqubit states can be described in terms of a density matrix. To classify states up to local equivalence it is necessary to study invariants that are polynomial in the density matrix parameters. Here we tackle the problem of not just counting the number of linearly independent polynomial invariants of given degree, but also identifying a suitable basis that can be used to generate them all quite explicitly. This is a classical invariant theory problem involving the group U(16) and its restriction to a particular subgroup U(2)xU(2). A complete solution is provided, including en route a few surprises and some interesting syzygies.
Summer 2004
Mathematical Physics Seminars
Summer 2004
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room G/109 in Goodricke College. The seminars are preceded by
tea from 4 pm. The typical length of the talks is about
1 hour.
Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Bernard Kay by email if you need further information.
Please also check the Departmental Events Calendar for other seminars which might be of interest. For example the Departmental Colloquium talks on Wednesdays sometimes are on mathematical physics.
Programme
Please note that this is the tentative evolving program. It is advisable to (reload and) recheck the page shortly before each talk. There is a
mailing list for the seminar announcements. For further details please contact
Bernard Kay
19 April Monday 4.20pm  Yvette FuentesGuridi (Oxford) Holonomic quantum computation in the presence of decoherence 
26th April Monday 4.20pm  Ed Copeland (Sussex) Trying to understand the nature of dark energy in the Universe 
13th May Thursday afternoon  No Seminar But ... There are some interesting MMath presentations 
17th May Monday 4.20pm  Alan George (York) Coupling the massive KleinGordon field to a boundary oscillator 
20th May Thursday 4.20pm  Andreas Winter (Bristol) Generic aspects of quantum entanglement 
24th May Monday 4.20pm  Alan George (York) Coupling the massive KleinGordon field to a boundary oscillator (continued) 
27th May Thursday 4.20pm  Gabor Toth (Eotvos University, Budapest) On N=1 supersymmetric boundary bootstrap 
17th June Thursday 4.20pm  Stefan Antusch (Southampton) Neutrino Mass Models 
28 June Monday 4.20pm  Zoltan Bajnok (Eotvos University, Budapest) Semiclassical SineGordon on the strip 
PhysicsFuentesguridiabstract2004
Abstract of Talk Holonomic quantum computation in the presence of decoherence
by Yvette FuentesGuridi (Oxford)
We investigate the effects of decoherence in the geometric evolution of states of a degenerate quantum system. This is done by generalizing the scheme for geometric phases in open systems to nonAbelian holonomies. The formalism is applied to estimate the errors produced by performing an universal set of holonomic quantum gates in the presence of an environment. We pinpoint the source of error in the scheme that must be corrected to achieve holonomic quantum computation completely robust to decoherence.
PhysicsWinterabstract2004
Abstract of Talk Generic aspects of quantum entanglement
by Andreas Winter (Bristol)
Probability theory has some insight to offer into the typical behaviour of states on large composite quantum systems. For example, because they are of measure zero in state space, product states are "never" seen when drawing a pure state uniformly at random. It may already come as a surprise that for large local dimension in a bipartite system the overwhelming majority of all pure states is in fact close to maximally entangled.
But even more is true: random subspaces of close to full dimension will with overwhelming probability contain only almost maximally entangled states. This implies that under a certain natural probability measure the generic mixed state will have almost maximal entanglement of formation. On the other hand, the distillability properties of these states can be shown to be very poor, both for EPR pairs and for secret key.
The techniques carry over to multiparty states, and offer a vision of "generic entanglement" as highly irreversible but potentially quite uniform  in contrast to the bewildering array of different types of entanglement in an exact classification. This is joint work with Patrick Hayden and Debbie Leung (Caltech).
Spring 2004
Mathematical Physics Seminars
Spring 2004
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room G/109 in Goodricke College. The seminars are preceded by
tea from 4 pm. The typical length of the talks is about
1 hour.
Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Bernard Kay by email if you need further information.
Please also check the Departmental Events Calendar for other seminars which might be of interest. For example the Departmental Colloquium talks on Wednesdays sometimes are on mathematical physics.
Programme
Please note that this is the tentative evolving program. It is advisable to (reload and) recheck the page shortly before each talk. There is a
mailing list for the seminar announcements. For further details please contact
Bernard Kay
15th January Thursday 4.20pm  Alexander Mikhailov (Leeds) Infinite dimensional automorphic Lie algebras 
19th January Monday 4.20pm  David McMullan (Plymouth) Charges in gauge theories 
22nd January Thursday 4.20pm  Bernard Kay (York) Quantum Field Theory in Curved Spacetime 1 
26th January Monday 4.20pm  Bernard Kay (York) Quantum Field Theory in Curved Spacetime 2 
29th January Thursday 4.20pm  Bernard Kay (York) Quantum Field Theory in Curved Spacetime 3 
2nd February Monday 4.20pm  Anne Taormina (Durham) Symmetries of string theory 
5th February Thursday 4.20pm  Atsushi Higuchi (York) Quantum Field Theory in Curved Spacetime 4 
9th February Monday 4.20pm  David Pearson (Hull) Spectral analysis of Schrodinger operators in Quantum Theory 
12th February Thursday 4.20pm  Atsushi Higuchi (York) Quantum Field Theory in Curved Spacetime 5 
16th February Monday 4.20pm  Tim Hollowood (Swansea) Integrability and gauge theories 
19th February Thursday 4.20pm  Atsushi Higuchi (York) Quantum Field Theory in Curved Spacetime 6 
26th February Thursday 4.20pm  Gary Gibbons (DAMTP, Cambridge) Consistent dimensional reductions from higher dimensional gravity and super gravity theories 
1st March Monday 4.20pm  Koenraad Audenaert (Bangor) There, and back again: Quantum theory and global optimisation 
4th March Thursday 4.20pm  Chris Fewster (York) Quantum Field Theory in Curved Spacetime 7 
8th March Monday 4.20pm  no seminar 
11th March Thursday 4.15pm G/010  Adrian Ottewill (University College, Dublin) Quantum fields near rotating black holes Note different venue and slightly earlier start 
15th March Monday 4.20pm  Chris Fewster (York) Quantum Field Theory in Curved Spacetime 8 
18th March Thursday 4.20pm  Chris Fewster (York) Quantum Field Theory in Curved Spacetime 9 
PhysicsAudenaertabstract2004
Abstract of Talk There, and Back Again: Quantum Theory and Global Optimisation
by Koenraad Audenaert (Bangor)
We consider a problem in quantum theory that can be formulated as an optimisation problem and present a global optimisation algorithm for solving it, the foundation of which relies in turn on a theorem from quantum theory. To wit, we consider the maximal output purity $\nu_q$ of a quantum channel as measured by Schatten $q$norms, for integer $q$. This quantity is of fundamental importance in the study of quantum channel capacities in quantum information theory. To calculate $\nu_q$ one has to solve a nonconvex optimisation problem that typically exhibits local optima. We show that this particular problem can be approximated to arbitrary precision by an eigenvalue problem over a larger matrix space, thereby circumventing the problem of local optima. The mathematical proof behind this algorithm relies on the Quantum de Finetti theorem, which is a theorem used in the study of the foundations of quantum theory.
We expect that the approach presented here can be generalised and will turn out to be applicable to a larger class of global optimisation problems. We also present some preliminary numerical results, showing that, at least for small problem sizes, the present approach is practically realisable.
Autumn 2003
Mathematical Physics Seminars
Autumn 2003
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room G/109 in Goodricke College. The seminars are preceded by
tea from 4 pm. The typical length of the talks is about
1 hour.
Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Bernard Kay by email if you need further information.
Please also check the Departmental Events Calendar for other seminars which might be of interest. For example the Departmental Colloquium talks on Wednesdays sometimes are on mathematical physics.
Programme
Please note that this is the tentative evolving program. It is advisable to (reload and) recheck the page shortly before each talk. There is a
mailing list for the seminar announcements. For further details please contact
Bernard Kay
22nd September Monday 2.15pm  Jason Szulc (York) Inequalities for marginal probabilities, quantum and classical 
13th October Monday 4.20pm  Mathematical Physics Group Meeting 
16th October Thursday 4.20pm  Akihiro Ishibashi (DAMTP, Cambridge) On stability of higher dimensional static black holes 
20th October Monday 4.20pm  Dan Tovey (Sheffield) Searching for Supersymmetric Dark Matter at Boulby Mine 
2325 October
 ABCKLM Meeting 
23rd October Thursday 4.30pm  Erika Andersson (Strathclyde) Generalised measurements in quantum mechanics Note unusual time and place: The venue for this talk is now Derwent College room D/056 (10 minutes' walk from Mathematics Department) because the talk will take place within the ABCKLM Meeting (see link above) 
27th October Monday 4.20pm  Sean Hartnoll (DAMTP, Cambridge) Black hole instabilities, thermodynamics and duality 
30th October Thursday 4.20pm  Davide Fioravanti (York) An idea of universality in theories with a mass scale 
3rd November Monday 4.20pm  Werner Nahm (IAS, Dublin) Conformal Field Theory and an extended Bloch group 
10th November Monday 4.20pm  Tomihiro Harada (QMW, London) Selfsimilar solutions, critical behaviour and convergence to attractor in gravitational collapse 
13th November Thursday 4.20pm  Jiannis Pachos (Imperial College, London) Coherent evolutions in one and two dimensional optical lattices. 
17th November Monday 4.20pm  Niall MacKay (York) The Mathematics and Physics of Yangians 1 
20th November Thursday 4.20pm  Michael Melgaard (Uppsala) Spectral Theory of Schr"{o}dinger and Dirac Operators with External Magnetic Fields. Part II: AharonovBohm magnetic fields and LiebThirring inequalities. Note This is the second of two talks. The first (which is subtitled Part I: Eigenvalue Asymptotics ) will be at 11.15 am on Wednesday 19th November in G/109 in the GANT seminar series. But it will not be necessary to have gone to that talk to understand this one. 
24th November Monday 4.20pm  Niall MacKay (York) The Mathematics and Physics of Yangians 2 
27th November Thursday 4.20pm  Viv Kendon (Imperial College, London) Quantum versions of random walks for quantum computing 
1st December Monday 4.20pm  Charles Young (DAMTP, Cambridge) Local conserved charges in supersymmetric sigma models 
4th December Thursday 4.20pm  Niall MacKay (York) The Mathematics and Physics of Yangians 3 
8th December Monday 4.20pm  Niall MacKay (York) The Mathematics and Physics of Yangians 4 
11th December Thursday 4.20pm  Niall MacKay (York) The Mathematics and Physics of Yangians 5 
ABCKLM Network Meeting
Network in Algebraic Geometry, Boundary Conformal Field Theory and Noncommutative Geometry
Seventh Network Meeting
University of York
23  25 October, 2003
Network Speakers Participants Programme Directions Accommodation Contacts
Information about the Network
The objective of this network is to bring together groups in the UK having a common goal in pursuing the deep connections between mathematics and physics, primarily algebraic geometry, operator algebras and quantum groups in pure mathematics and conformal field theory, string theory and statistical mechanics in mathematical and theoretical physics. For more information and details of past meetings see the network's webpage.
Speakers:
Participants: The meeting is open to all. Please register with the local organiser to receive further information. There is no conference fee. Some funds are available to fund participants belonging to one of the network nodes.
 Bath: Alexander Kasprzyk (d)
 Cambridge: Alessio Corti, Jasbir Nagi (d)
 Cardiff: Roger Behrend (d), Partha Sarathi Chakraborty (d), David Evans (d), Daniel Hoyt (d)
 Durham: Peter Bowcock, Patrick Dorey (d), Thomas Keef
 London: Jan Grabowski (d), Shahn Majid (d), Alice Rogers (d), Reidun Twarock (d), Gerard Watts (d), Peter West
 Swansea: Edwin Beggs (d)
 Warwick: Katrin Wendland (d)
 York: Ed Corrigan (d), Gustav Delius (d), Chris Fewster, Davide Fioravanti (d), Alan George, Bernard Kay, Niall MacKay (d), Max Nazarov, Evgueni Sklyanin, Tony Sudbery, Cristina Zambon (d)
as well as: Erika Andersson (Strathclyde),
Zoltán Bajnok (d) (Budapest), Vasily Golyshev,
Lászlo Palla (d) (Budapest),
Aidan Schofield (d) (Bristol),
Jakob Stix (d) (Bonn),
Gábor Takács (d) (Budapest)
Programme: We have booked Derwent Terrace Room from the morning of Thursday 23rd of October until the afternoon of Saturday 25th of October. This room will serve as our base room which we will use for tea, coffee and discussions while the talks will take place in nearby lecture rooms.
Thursday 23^{rd} October
morning  Gathering in Derwent Terrace Room 
1:00 pm  Lunch 
2:00 pm  Evgueni Sklyanin Separation of variables and related topics in room D/056 
3:15 pm  Zoltán Bajnok Boundary quantum field theories in room D/056 
4:30 pm  Erika Andersson: Generalised measurements in quantum mechanics in room D/056 
6:45 pm  Dinner in the Roger Kirk centre 
Friday 24^{th} October
8:30 am  Breakfast in Wentworth College 
9:30 am  Peter West tba in room L/037 
11:30 am  Alessio Corti and Vasily Golyshev in room D/056 
1:00 pm  Lunch 
2:15 pm  Alice Rogers: Morse Theory on Phase Space in room C/A/101 
3:30 pm  Reidun Twarok: Mathematical virology in room D/016 
4:30 pm  Tea and Coffe in Derwent Coffee room 
5:00 pm  Aidan Schofield: Noncommutative moduli of vector bundles in room D/016 
6:45 pm  Dinner in the "Go Down Restaurant" 
Saturday 25^{th} October
8:30 am  Breakfast in Wentworth College 
9:30 am  Jakob Stix: Introduction to logarithmic Geometry in room C/A/101 
11:00 am  Shahn Majid: Fock space representation for Anyons in room D/056 
12:15 pm  Lunch in Vanbrugh College 
There will be breaks with refreshments between all talks.
Directions: How to Reach the University of York.
The meeting will take place mostly in Derwent College. This is building 23 on the campus map
When you arrive at York railway station you can either take bus no 4 to Heslington Hall (building 1 adjacent to Derwent College) or take a taxi and ask the driver to drop you at Derwent College. Alternatively, in case you have a lot of luggage and will be staying in Wenworth College, see below, you could take the taxi to Wentworth College and then walk to Derwent College from there (5 or 10 minutes walk across campus).
For more information see "How to Reach the University of York".
Accommodation: The following participants will be staying in Wentworth College (arrival and departure dates in parentheses):
 Zoltán Bajnok (2326)
 Edwin Beggs (2325)
 Roger Behrend (2325)
 Partha Chakraborty (2325)
 David Evans (2325)
 Jan Grabowski (2325 twin room)
 Daniel Hoyt (2325 twin room)
 Alexander Kasprzyk (2325 twin room)
 Shahn Majid (2325)
 Jasbir Nagi (2325 twin room)
 Lászlo Palla (2326)
 Alice Rogers (2325)
 Aidan Schofield (2325)
 Jakob Stix (2325)
 Gábor Takács (2326)
 Gerard Watts (2325)
 Katrin Wendland (2325)
 Peter West (2324)
The following participants will be staying in Victoria Villa for the first night only before moving into Wentworth College:
 Alexander Kasprzyk
 Jasbir Nagi
 Roger Behrend
Contacts: For further information contact
Gustav W Delius (York) or
David E Evans (Cardiff).
BACK TO ABCKLM NETWORK BACK TO MATHEMATICAL PHYSICS GROUP AT YORK
PhysicsAnderssonabstract2003
Abstract of Talk Generalised measurements in quantum mechanics
by Erika Andersson (Strathclyde)
In standard textbooks on quantum mechanics, a quantum measurement is usually described as a projection in the eigenbasis of the measured observable. This definition of projective (von Neumann) measurements is, however, too narrow. It does not allow us to describe all possible experimental measurement procedures. For example, we cannot accommodate joint measurements of noncommuting observables. Also, in a real experiment, with detector inefficiencies and other imperfections, what results is generally not a projective measurement on the original measured quantum system.
Generalised quantum measurements can describe any measurement that can be realised on a quantum system (provided that quantum mechanics holds). They are often called POM or POVM measurements, and are essentialy obtained by removing the requirement that the measurement operators have to be projectors. This talk will introduce generalised measurements and explain why they are useful. Generalised measurements have important applications for example in quantum communication theory, where one wants to know exactly what the optimal measurement strategy for a certain kind of signal is. They can also describe joint measurements of non commuting observables, as well as real experimental situations with imperfect detectors.
PhysicsHaradaabstract2003
Abstract of Talk Selfsimilar solutions, critical behaviour and convergence to attractor in gravitational collapse
by Tomihiro Harada (QMW)
General relativity as well as Newtonian gravity admits selfsimilar solutions due to the scaleinvariance. This talk reviews selfsimilar solutions and their relevance to gravitational collapse. In particular, our attention is mainly paid on the crucial role of selfsimilar solutions in the critical behavior and attraction in gravitational collapse. Implications to cosmic censorship are also discussed.
PhysicsKendonabstract2003
Abstract of Talk Quantum versions of random walks for quantum computing
by Viv Kendon (Imperial)
Will we be using a quantum computer for numerical simulations in the next decade? Quantum computing offers the potential for exponentially more efficient calculations than classical computers. But not for all problems, we know of a set that make use of a quantum version of Fourier Transforms for their speed up (including factoring large numbers) and one example using a quantum version of a random walk. Other classes of problems, such as searching an unsorted database, can have at most a quadratic speed up. And then there are all the difficulties of actually building a quantum computer... I will give an introductory overview of quantum computing, suitable for the nonspecialist, in the course of which my own work on quantum versions of random walks will get a brief mention.
PhysicsNahmabstract2003
Abstract of Talk Conformal Field Theory and an extended Bloch group
by Werner Nahm (IAS, Dublin)
Integrable perturbations of conformal quantum field theories in two dimensions and invariants of hyperbolic manifolds are both described by an extension of the Bloch group, an object in algebraic Ktheory. For the quantum field theories, the Bethe ansatz yields finite order elements in this group, which statisfy certain algebraic equations. Examples are provided by pairs of ADET diagrams, and in the case of two Atype diagrams all solutions of these equations are obtained.
PhysicsPachosabstract2003
Abstract of Talk Coherent evolutions in one and two dimensional optical lattices
by Jiannis Pachos (Imperial)
We consider the controlled manipulation of one dimensional bosonic or fermionic optical lattices, induced by tunnelling or collisions of the atoms within the lattice. As an application, we discuss the implementation of quantum computation where each atom provides one qubit. The resulting quantum register is robust against dephasing due to longitudinal lattice decoherence. Further studies concern one or two dimensional optical lattices and result in solid state models with new intriguing three body interactions.
Summer 2003
Mathematical Physics Seminars
Summer 2003
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room G/109 in Goodricke College. The seminars are preceded by
coffee from 4 pm. The typical length of the talks is about
1 hour.
Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Clare Dunning by email if you need further information.
Please also check the Departmental Events Calendar for other seminars which might be of interest. For example the Departmental Colloquium talks on W ednesdays sometimes are on mathematical physics.
Programme
Please note that this is the tentative evolving program. It is advisable to recheck the page shortly before each talk. There is a
mailing list for the seminar announcements. For further details please contact
Clare Dunning
28 April Monday 4.20pm  José Miguel Figueroa y O'Farrill (Edinburgh) Plane wave limits in string and gauge theory 
6 May Tuesday 11:30 am Unusual Time  Mark Gould (Brisbane) Classification of unitary representations of simple Lie superalgebras 
22nd May Thursday 4.20pm  Evgueni Sklyanin (York) Qoperator and separation of variables for Jack polynomials 
29th May Thursday 4.20pm  Betti Hartmann (Durham) Monopoles and "hairy" black holes 
2nd June Monday 4.20pm  Valeria Del Prete (KCL) A theoretical model for population coding of mixed continuous and discrete stimuli: from the linear rise to the asymptotic regime. 
5th June Thursday 4.20pm  Chris Fewster (York) Stability of quantum systems at three scales 
9th June Monday 4.20pm  Cristina Zambon (York) Classically integrable field theories with boundary conditions 
16th June Monday 4.20pm  Andy Hone (UKC) Peakons, Poisson brackets and a functional equation. 
19th June Thursday 4.20pm  Hugh Jones (Imperial) PT symmetry versus Hermiticity in Quantum Mechanics and Quantum Field Theory 
23rd June Monday 4.20pm  Jorma Louko (Nottingham) Higher dimensional Einstein black holes and AdS/CFT conjecture 
26th June Thursday 4.20pm  Roger Behrend (Cardiff) Reflections on the Reflection Equation 
7 July Monday 4.20pm  Martin Halpern (Berkeley) Twisted Open Strings from Closed Strings: The WZW Orientation Orbifolds 
22nd July Tuesday 4.15pm  Christopher Fuchs (Bell Labs) What is the Difference between a Quantum Observer and a Weatherman? 
25th July Friday 2.15pm  Ruediger Schack (Royal Holloway) Compatible quantum state assignments 
8th September Monday 2.15pm  Rainer Verch (Max Planck Institute, Leipzig) Generally covariant quantum field theory and spin and statistics for quantum fields on manifolds 
22nd September Monday 2.15pm  Jason Szulc (York) Inequalities for marginal probabilities, quantum and classical

Spring 2003
Mathematical Physics Seminars
Spring 2003
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room G/109 in Goodricke College. The seminars are preceded by
coffee and biscuits. The typical length of the talks is about
1 hour.
Information on How to Reach the University is available. Goodricke College is building 24 on the campus map. Please contact Gustav Delius by email if you need further information.
Please also check the Departmental Events Calendar for other seminars which might be of interest. For example the Departmental Colloquium talks on Wednesdays sometimes are on mathematical physics.
Programme
Please note that this is the tentative evolving program. It is advisable to recheck the page shortly before each talk. There is a
mailing list for the seminar announcements. For further details please contact
Dr. B.S. Kay or
Dr. G.W. Delius.
Mathematical Physics Seminars at the University of York
Mathematical Physics Seminars Spring 2003 Abstracts Fay Dowker (Imperial) A spontaneous collapse model on a lattice The spontaneous collapse models of Ghirardi, Rimini and Weber (GRW), Pearle and others represent a promising direction of research towards an observer independent theory of fundamental matter. These models were first proposed in a nonrelativistic framework and since then much attention has focused on the search for appropriately relativistic models. This is not only important in its own right, but seems to be a prerequisite to any hope of applying collapse model ideas to quantum gravity. I will present a simple collapse model for a field theory, defined on a $1+1$ null lattice. Being a lattice model, it doesn't enjoy exact Lorentz invariance and so it may be argued that it is not ``relativistic'' at all. However, it is not unreasonable to hope that Lorentz invariance will be attained in an appropriate continuum limit. Moreover, in the view of some workers, the aspect of spacetime that is fundamental and survives its encounter with its quantum nemesis is its causal structure and, further, that this fundamental causal structure is discrete. If one is looking for a development of quantum theory suited to such beliefs about quantum gravity, our model has many attractive features: it is discrete, there is a causal structure, and there is a local evolution rule tied to that causal structure. I will show that it is very ``local'' in construction, though it gives rise to nonlocal correlations (as expected by Bell's Theorem). I will also show that, despite the nonlocal correlations, external agents cannot use the field to send superluminal signals. Jon Links (Brisbane) Exactly solvable model for atomicmolecular BoseEinstein condensates Abstract: The prospect of producing a BoseEinstein condensate comprised of a coherent superposition of atomic and diatomic molecular states has been considered theoretically for some years, but only recently been realised experimentally. A simple two mode model for this phenomenon will be presented which admits an exact solution through the algebraic Bethe ansatz. As a first step towards understanding the behaviour of the model, both an asymptotic and numerical analysis is conducted for a particular limit. From this the ground state properties, scaling behaviour and quantum dynamics are examined.

Autumn 2002
Mathematical Physics Seminars
Autumn 2002
22 August Thursday 4.20pm  Masashi Hamanaka (Univ. of Tokyo, YITP) Noncommutative ADHM construction 
14 October Monday 4.20pm  Tony Sudbery (York) Nocollapse interpretations of quantum mechanics 
17 October Thursday 4.20pm  Bernard Kay (York) Remarks on the Foundations of Quantum Mechanics 
21 October Monday 4.20pm  Postponed due to illness Deborah Konkowski (US Naval Academy) Are classically singular spacetimes quantummechanically singular as well? 
24 October Thursday 4.20pm  Leah Henderson (Bristol) Optimal entanglement generation from quantum operations 
28 October Monday 4.20pm  Ed Corrigan (York) Graduate Lectures on String Theory 
31 October Thursday 4.20pm  Atsushi Higuchi (York) Radiation reaction in scalar QED 
4 November Monday 4.20pm  Ed Corrigan (York) Graduate Lectures on String Theory 
7 November Thursday 4.20pm  Deborah Konkowski (US Naval Academy) Are classically singular spacetimes quantummechanically singular as well? 
11 November Monday 4.20pm  Ed Corrigan (York) Graduate Lectures on String Theory 
14 November Thursday 4.20pm  Marco Bellacosa (Bologna) Nonlinear Integral Equations for Quantum Integrable Models with Boundaries 
18 November Monday 4.20pm  Ed Corrigan (York) Graduate Lectures on String Theory 
21 November Thursday 4.20pm  Wojtek Zakrzewski (Durham) Some Aspects of the Modified Nonlinear Schrodinger Equation 
25 November Monday 4.20pm  Ed Corrigan (York) Graduate Lectures on String Theory 
28 November Thursday 4.20pm  Mitch Pfenning (York) Quantum Inequalities 
2 December Monday 4.20pm  Ed Corrigan (York) Graduate Lectures on String Theory 
5 December Thursday 4.20pm  Joe Hilling (York) The History Projector Operator Formalism of Consistent Histories 
9 December Monday 4.20pm  Ed Corrigan (York) Graduate Lectures on String Theory 
12 December Thursday 4.20pm  Emily King (York) Applications of consistent histories 
Summer 2002
Mathematical Physics Seminars
Summer 2002
22 April Monday 4.20pm  Richard Woodard (University of Florida) A NonTechnical (Honest!) Description of the Problem of Quantum Gravity 
2 May Thursday 4.20pm  Patrick Dorey (Durham) Exact Smatrices for the qstate Potts models 
6 May Monday 4.20pm  Gustav W Delius (York) Graduate Lectures on Solitons and Boundaries: Classical Soliton Solutions 
9 May Thursday 4.20pm  Theodora Ioannidou (Kent) Bogomolny YangMillsHiggs Solutions in (2+1) antide Sitter Space 
13 May Monday 4.20pm  Paul Sutcliffe (Kent) Solitons in the Heart 
16 May Thursday 4.20pm  Charis Anastopoulos (Utrecht) Quantum mechanical histories and interference phases 
20 May Monday 4.20pm  Bernhard Baumgartner (Vienna) Order relations for sets and inequalities for entropies 
21 May Tuesday 5.20pm Note special time and venue: V/123  LMS Hardy Lecture Alexander Its The nonlinear Schroedinger equation on the halfline and on the interval 
27 May Monday 4.20pm  Stephen Siklos (DAMTP) Singularities and invariants in general relativity 
30 May Thursday 4.20pm  Hendryk Pfeiffer (DAMTP) Spin foam models in quantum gravity 
6 June Thursday 4.20pm  S.M. Chitre (Tata Institute) The seismic sun and solar neutrinos 
13 June Thursday  Meeting of the North British Mathematial Physics Seminar 
17 June Monday 4.20pm  Thomas Roman (Connecticut) Constraints on Spatial Distributions of Negative Energy 
20 June Thursday 4.20pm  Tony Sudbery (York) Quantum Fallacies A guided discussion 
Spring 2002
Mathematical Physics Seminars
Spring 2002
14 January Monday 4.20pm  Jose FigueroaOFarrill (Edinburgh) Lie Branes: recent results 
17 January Thursday 4.20pm  Larry Ford (Tufts) Focusing Vacuum Fluctuations 
21 January Monday 4.20pm  Katsushi Ito (Tokyo Institute of Technology) Scattering of noncommutative solitons 
24 January Thursday 4.20pm  Kevin Graham (King's College, London) Perturbations of Conformal Field Theory by Boundary Condition Changing Operators 
31 January Thursday 4.20pm  Atsushi Higuchi (York) Discussion on Topological KTheory 
4 Feburary Monday 4.20pm  Atsushi Higuchi (York) Discussion on Topological KTheory 
5 February Tuesday 4.20pm (Note unusual day)  Michael Atiyah (Edinburgh) Ktheory and charges 
7 Feburary Thursday 4.20pm  Yann Golanski (NNDG York) Modelling of early stages of stellar formation 
11 February Monday 4.20pm  James Gray (Newcastle) Moving branes in Heterotic Mtheory cosmology 
14 February Thursday 4.20pm  Ian Lawrie (Leeds) Dissipation and friction in the equations of motion for scalar fields 
18 February Monday 4.20pm  David Toms (Newcastle) Quantum Fields off the Brane 
21 February Thursday 4.20pm  Andrei Bytsko (Steklov Institute, St.Petersburg) Hamiltonians for higher spin XXZ chains 
11 March Monday 4.20pm  Robert Oeckl (Marseille) tba 
Autumn 2001
Mathematical Physics Seminars
Autumn 2001
The seminar takes place on
Mondays and
Thursdays: from
4:20 pm onwards in the very relaxed atmosphere of
Room V/131 in Vanbrugh College. The seminars are preceeded by
coffee and biscuits. The typical length of the talks is about
1 hour. For further details please contact
Dr. B.S. Kay or
Dr. G.W. Delius.
15 October Monday 4.20pm  Jason Szulc (York) The Nobelprizewinning experiment on BoseEinstein condensation 
18 October Thursday 4.20pm  Atsushi Higuchi (York) Lowfrequency scalar absorption cross sections for stationary black holes 
22 October Monday 4.20pm  Alan George (York) Quintessence 
25 October Thursday 4.20pm  Ruth Gregory (Durham) Braneworld instantons 
29 October Monday 4.20pm  Mitch Pfenning (York) Radiation reaction in electromagnetism and general relativity: I electromagnetism 
1 November Thursday 4.20pm  Mitch Pfenning (York) Radiation reaction in electromagnetism and general relativity: II gravitation 
5 November Monday 4.20pm  Chris Fewster (York) Microlocal Analysis This seminar forms part of the York Mathematics Department Series of expository seminars for staff and students 
8 November Thursday 4.20pm  Ian Jack (Liverpool) Finite noncommutative theories 
12 November Monday 4.20pm  Tony Sudbery and Jason Szulc (York) Report on the Turin Meeting on Quantum Information (Note that the planned talks by Jochen Weller, previously announced in this slot, have had to be cancelled.) 
15 November Thursday 4.20pm  (no seminar) 
19 November Monday 4.20pm  Ian McIntosh (York) A rough and ready guide to cohomology. Part 2: Cech cohomology This seminar forms part of the York Mathematics Department Series of expository seminars for staff and students 
22 November Thursday 4.20pm  Gustav Delius (York) Quantum group symmetry in the boundary sineGordon model and soliton reflection amplitudes 
26 November Monday 4.20pm  John Loftin (Columbia) Toward a compactification of the moduli space of convex RP(2) surfaces 
3 December Monday 4.20pm  Atsushi Higuchi (York) The renormalization group This seminar forms part of the York Mathematics Department Series of expository seminars for staff and students 
10 December Monday 4.20pm  Chongsun Chu (Durham) Aspects of noncommutative gauge theories 
13 December Thursday 4.20pm  Rafael Nepomechie (Miami) Supersymmetric integrable boundary QFT in 1+1 dimensions 
Summer 2001
Mathematical Physics Seminars
Summer 2001
Clicking on the highlighted dates in the calendar brings you to the seminar details in the programme below.
April  Mo  Tu  We  Th  Fr  Sa  So        1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30         May  Mo  Tu  We  Th  Fr  Sa  So   1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31             June  Mo  Tu  We  Th  Fr  Sa  So      1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30          
Times & Location
Mondays & Thursdays:  Talks start at 4:20 pm. They are preceeded by coffee and biscuits. The seminars are open ended but there will be a short break after about 50 minutes. They take place in the very relaxed atmosphere of Room V/131 in Vanbrugh College. 
Wednesdays:  These are the Departmental Seminars and are supposed to be accessible to a general mathematics audience. They take place in room V/131, Vanbrugh College, at 4.00 pm. Tea will be available at 3.30 p.m. in the Senior Common Room, Vanbrugh College. 
Information on How to Reach the University is available. Vanbrugh College is building 25 on the campus map. Please contact Gustav Delius by email if you need a parking permit or would like further information.
Programme
This term we will have
lectures by Evgueni Sklyanin on selected topics in classical and quantum integrable models every Mondays starting on May 14.
Please note that this is the tentative evolving program. It is advisable to recheck the page shortly before each talk. For further details or to be placed on the mailing list please contact Dr. B.S. Kay or Dr. G.W. Delius.
30 April Monday 4.20pm  Dr Konstantina Savvidou (Imperial) Time in histories theory 
3 May Thursday 4.20pm  Dr Pascal Baseilhac (York) Expectation values of descendent fields in integrable quantum field theories 
10 May Thursday 4.20pm  Dr Anastasia Doikou (York) Principal chiral model scattering and the alternating quantum spin chain 
16 May Wednesday 4.00pm  Professor Paul Glendinning (UMIST) On the unique expansion of numbers in noninteger bases: a dynamical systems approach 
17 May Thursday 4.20pm  Dr Rod Crewther (Adelaide) Why I want YangMills topological charge to take noninteger values 
23 May Wednesday 4.00pm  Dr Alan Beardon (Cambridge) Continued Fractions: Old and New 
24 May Thursday 4.20pm  Professor Rex Godby (York) Manybody perturbation theory for electrons in real materials 
30 May Wednesday 4.00pm  Dr Martin Matthieu (Queen's, Belfast) Elementary Operators on Calkin Algebras 
31 May Thursday 4.20pm  Dr Chris Fewster (York) Quantum Inequalities for the Dirac Field 
6 June special time Wednesday 4.20pm  Ryu Sasaki (YITP, Kyoto University) Hierarchies of Spin Models related to CalogeroMoser Models (hepth/0105197) 
7 June Thursday 4.20pm  Daniel Vanzella (Sao Paulo) Decay of accelerated protons and the FullingDaviesUnruh effect 
13 June Wednesday 4.00pm  Dr Julian Barbour The dynamics of pure shape 
14 June Thursday 4.20pm  Dr Julian Barbour Relativity without Relativity 
15 June special time Friday 11.30am  Dr Laszlo Feher (Szeged, Hungary) Interpretations and constructions of dynamical rmatrices 
28 June Thursday 4.20pm  Professor Peter Holdsworth (ENS Lyon) Spin liquides glasses and ice: degeneracy and degeneracy lifting in frustrated magnetism 
9 July special time Monday 4.20pm  Prof Larry Ford (Tufts) Where is the Negative Energy?  Constraints on Spatial Distributions of Negative Energy in Quantum Field Theory 
Lectures by E.K. Sklyanin
Mondays 4:20pm to 6pm, starting May 14.
Abstract:
The lecture course covers a few advanced topics from the theory of integrable systems and is intended for the postgraduate and postdoctoral audience who is already familiar with the basics (definition of integrability according to LiouvilleArnold, Lax matrix, rmatrix, quantum group, Bethe Ansatz).
The topics include: Bäcklund transformations, Qoperator, separation of variables, integrable boundary conditions. The variety of techniques is illustrated on a few examples: Toda lattice, XXX magnetic chain, CalogeroMoser model.
Detailed plan of lectures:
 Integrability: a brief review of the basics
LiouvilleArnold's definition of integrability. Isospectral transform method: Lax matrix. LiePoisson groups: rmatrix. Symplectic leaves of rmatrix Poisson bracket. XXX magnetic chain as the generic integrable model associated to the sl_{2}invariant rmatrix. Degenerations of XXX model: DST model, Toda lattice, Gaudin model. Quantization. Correspondence rules. Quantum canonical transformations: Fock formula. Quantum groups, Yangians. XXX magnetic chain, algebraic Bethe Ansatz.
 Bäcklund transformations
Axioms of BT: algebraicity, locality, canonicity, commutativity (Veselov theorem), spectrality. General construction of BT for the models associated to the sl_{2}invariant rmatrix. Examples: Toda lattice, XXX chain, CalogeroMoser (Ruijsenaars) model.
 Qoperator
History: motivations, Baxter's construction, PasquierGaudin, BazhanovLukianovZamolodchikov works. Relation of Q and BT. Qoperator for the XXX model  a detailed study. Universal sl_{2}invariant Rmatrix. Qoperator as trace of a monodromy matrix. 3 kinds of Qoperators. Factorization of the Rmatrix and the Qoperator. Fusion and wronskian identities. Kernels and symbols of Q.
 Separation of variables
Definitions (classical and quantum case). Classical SoV. General construction: poles of the eigenvectors of the Lax matrix. Normalization problem. Examples: Toda lattice, XXX model, CalogeroMoser model.
Relation of SoV and BT (Q). SoV from BT (KuznetsovSklyanin). BT from SoV (KuznetsovVanhaecke).
Quantum SoV. Examples: Toda lattice, XXX model, Macdonald polynomials.
 Integrable boundary conditions
General construction based on exchange algebras. Comodules over quantum groups. Examples: XXX model, Toda lattice, Nonlinear Schröodinger equation. Bethe Ansatz, SoV, Qoperator for the systems with boundary.
Spring 2001
Mathematical Physics Seminars
Spring 2001
Clicking on the highlighted dates in the calendar brings you to the seminar details in the programme below.
January  Mo  Tu  We  Th  Fr  Sa  So  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31       February  Mo  Tu  We  Th  Fr  Sa  So     1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28       March  Mo  Tu  We  Th  Fr  Sa  So     1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28      
Times & Location
Mondays & Thursdays:  Talks start at 4:20 pm. They are preceeded by coffee and biscuits. The seminars are open ended but there will be a short break after about 50 minutes. They take place in the very relaxed atmosphere of Room V/131 in Vanbrugh College (building 25 on campus map). 
Wednesdays:  These are the Departmental Seminars and are supposed to be accessible to a general mathematics audience. They take place in room V/131, Vanbrugh College, at 4.00 pm. Tea will be available at 3.30 p.m. in the Senior Common Room, Vanbrugh College. 
The seminar slots on Mondays and Thursdays which are not filled by a regular seminar talk will be used for the
Dbrane reading seminar.
Programme
Please note that this is the tentative evolving program. It is advisable to recheck the page shortly before each talk. For further details or to be placed on the mailing list please contact
Dr. B.S. Kay or
Dr. G.W. Delius.
11 January Thursday 4.20pm  Dr Roberto Tateo (Durham) Perturbed boundary conformal field theory and quantum mechanics 
15 January Monday 4.20pm  Spyros Kouris (York) Graviton twopoint function in de Sitter spacetime 
18 January Thursday 4.20pm  Clare Dunning (York) Ordinary differential equations and integrable quantum field theories 
22 January Monday 4.20pm  Dr Keith Anguige Isotropic Cosmological Singularities 
24 January Wednesday 4 pm  Dr Steven Bramwell (University College London) Universal Fluctuations in Correlated Systems 
25 January Thursday 4.20pm  Professor Dmitri Vassiliev (Bath) Spectral asymptotics for partial differential operators and microlocal analysis 
29 January Monday 4.20pm  Jason Szulc (York) Shor's factorisation algorithm 
31 January Wednesday 4 pm  Dr Benjamin Steinberg (Porto) What is partial symmetry? 
1 February Thursday 4.20pm  Dr Davide Fioravanti (Durham) DE RERUM NATURA id est THE IMPORTANCE OF BEING SYMMETRY 
7 February Wednesday 4 pm  Dr Paolo Papi (Rome) An overview on adnilpotent ideals of Borel subalgebras 
8 February Thurday 4.20pm  Dr Andrew Mathas (Sydney) Affine Hecke algebras, ArikiKoike algebras and Fock spaces 
12 February Monday 4.20pm  Dr Clifford Johnson (Durham) Gauge Theory Dynamics from DBrane Probes 
13 February Tuesday 10.15pm  Dr Evgueni Sklyanin (St. Petersburg) Note that this is not a regular seminar talk but a presentation in connection with the readership position in our group. 
14 February Wednesday 4 pm  Professor J Greenlees (Sheffield) Implausible equivalences and duality 
15 February Thurday 4.20pm  Dr Niall MacKay (York) Vibrations of symmetric molecules and the Buckyball 
19 February Monday 4.20pm  Professor Vladimir Rittenberg (Bonn) The twocomponent Burgers equation and applications to stochastic processes 
21 February Wednesday 4 pm  Professor A Veselov (Loughborough) Configurations of hyperplanes in integrable systems 
26 February Monday 4.20pm  Dr Vadim Kuznetsov (Leeds) Bäcklund transformations go digital 
28 February Wednesday 4 pm  Professor P Glendinning (UMIST) Postponed because of bad weather On the unique expansion of numbers in noninteger bases: a dynamical systems approach 
7 March Wednesday 4 pm  Dr M Dritschel (NewcastleonTyne) to be announced 
7 March Thursday 4 pm  Professor Tony Sudbery (York) Groups, geometries and mechanics 
12 March Monday 4.20pm  Dr Konstantina Savvidou cancelled due to illness 
22 March Thursday 4.20pm  Professor Tohru Eguchi (Tokyo) String propagation on singular CalabiYau manifolds 
Mathematical Physics Seminars at the University of York
Mathematical Physics Seminars Spring 2001 Abstracts Paolo Papi (Rome I) An overview on adnilpotent ideals of Borel subalgebras In a complex simple Lie algebra with a fixed Borel subalgebra b, an adnilpotent ideal is an ideal of b whose elements are adnilpotents. We will describe various approaches to the problem of encoding and enumerating such objects, with applications to representation theory and combinatorics. Andrew Mathas (Sydney) Affine Hecke algebras, ArikiKoike algebras and Fock spaces We describe the classification of the simple modules of the affine Hecke algebras of type A and the ArikiKoike algebras. The key result is a deep result of Ariki's which builds upon work of Kazhdan, Lusztig and Ginzburg which connections the representation theory of these algebras with the representation theory of the quantum group of the affine special linear groups. John Greenlees (Sheffield) Implausible equivalences and duality The talk arises from the idea that (fairly commutative) algebra is a branch of topology and that (fairly commutative) topology is a branch of algebra. The aim is to give a framework in which the following phenomena can be treated simultaneously. However, the talk will only introduce a few of these examples and it should give a very concrete treatment.  Vector space duality
 Poincar'e duality (of algebras, manifolds, ...)
 Duality enjoyed by polynomial rings and by k[t^2,t^3] (for instance) but not by k[t^3,t^5,t^7]
 Koszul duality (e.g. the correspondence between modules over Q[t] and modules over Q[t]/t^2).
 classification of invariants of spaces with circle actions
Sasha Veselov (Loughborough) Configurations of hyperplanes in integrable systems The problem of classification of all integrable generalisations of the quantum CalogeroMoser system led to a new notion of the socalled locus configurations of hyperplanes. Such configurations turned out to be important for several other problems (for example, the classical Hadamard problem in the theory of Huygens' principle, the generalised WDVV equation). In the talk these configurations and the relevant results found by Berest, Chalykh, Feigin and the speaker will be discussed.

Summer 2000
Mathematical Physics Seminars
Summer 2000
We have a seminar twice a week:
Days:  Mondays and Thursdays 

Time:  talk at 4:15 pm, preceeded by coffee and biscuits The seminars are open ended but there will be a short break after about 50 minutes. 

Location:  Mondays in room G/010 in Goodricke College (building 22 on campus map), Thursdays in V/131 in Vanbrugh College (building 25 on campus map) 

Other mathematical physics seminars take place in the Wednesday Departmental Seminar series and for convenience these too are listed in the programme below.
Wednesday, 3 May:  Departmental Seminar at 4:00 in V/131 JY Thibou (Paris) Introduction to the Combinatorics of Ribbon Tableaux 
Thursday, 4 May:  Niall MacKay (York) The Principal Chiral Model on the HalfLine 
Monday, 8 May:  John Cardy (Oxford) Conformal Field Theory and Percolation 
Wednesday, 10 May:  Departmental Seminar at 4.00 in V/131 T Sapatinas (Kent) An introduction to wavelet decomposition and shrinkage 
Monday, 15 May:  Francois Englert (Brussels) The FeffermanGraham ambiguity and the holographic principle 
Wednesday, 17 May:  Departmental Seminar at 4:30 in V/131 Peter Phillips (Yale) Trends and Spurious Regression 
Monday, 22 May:  Sergei Lukyanov (Rutgers) Finite temperature expectation values of local fields in the sinhGordon model 
Wednesday, 24 May:  Departmental Seminar at 4:00 in V/131 Fran Burstall (Bath) Integrable systems in Conformable Geometry 
Thursday, 25 May:  Reidun Twarock (York) An aperiodic analog to the Virasoro algebra via quasicrystal techniques 
Wednesday, 31 May:  Departmental Seminar at 4:00 in V/131 Stephen Bramwall (University College London) Universal Fluctuations in Correlated Systems 
Wednesday, 7 June:  Departmental Seminar at 4:00 in V/131 Michael Berry (Bristol) The architecture of diffraction catastrophes 
Monday, 12 June:  Peter Goddard (Cambridge) An approach to Conformal Field Theory 
Wednesday, 14 June:  Departmental Seminar at 4:00 in V/131 Paul Turner (HeriotWatt) Homotopy Quantum Field Theories 
Thursday, 22 June:  Don Marolf (Syracuse) String/MBranes for relativists 
Thursday, 29 June:  Tony Sudbery (York) Why Am I Me? and other interesting questions 
Monday, 3 July:  Ryu Sasaki (Yukawa Institute, Kyoto) The Quantum CalogeroMoser Model 
Monday, 10 July:  AM Semikhatov (Lebedev and Durham) Integrable Representations as Collective (``Quasiparticle'') Excitations 
Spring 2000
Mathematical Physics Seminars
Spring 2000
We have two series of weekly Mathematical Physics seminars:
Monday seminars take place at 4.15 in room G/010
Thursday seminars take place at 4.15 in room V/131 (preceded by coffee at 4.00 in V/135).
20 January:  Jorma Louko (Nottingham) EinsteinKepler Problem in 2+1 Dimensions 
27 January:  Pascal Baseilhac (York) Reflection Amplitudes of NonSimply Laced Toda Theories and Thermodynamic Bethe Ansatz 
3 February:  Anastasia Doikou (Durham) Solving the BetheAnsatz Equations 
10 February:  Everyone Informal Discussion on Supersymmetric Quantum Mechanics 
17 February:  Nicolai Kitanine (York) Correlation Functions in the XXZ Model 
24 February:  Everyone Informal Discussion on Boundary Conformal Field Theory and String Theory 
2 March:  Malcolm Ludvigsen (York) Timelike Infinity and the Final State of Black Holes 
9 March:  Tony Sudbery (York) Entanglement 
16 March:  Chris Barton (York) Magic Squares of Lie algebras 
Autumn 2000
Mathematical Physics Seminars
Autumn 2000
Clicking on the highlighted dates in the calendar brings you to the seminar details in the programme below.
October  Mo  Tu  We  Th  Fr  Sa  So        1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31        November  Mo  Tu  We  Th  Fr  Sa  So    1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30             December  Mo  Tu  We  Th  Fr  Sa  So      1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20  21  22  23  24  25  26  27  28  29  30  31         
Times & Location
Mondays & Thursdays:  Talks start at 4:20 pm. They are preceeded by coffee and biscuits. The seminars are open ended but there will be a short break after about 50 minutes. They take place in the very relaxed atmosphere of Room V/131 in Vanbrugh College (building 25 on campus map). 
Wednesdays:  These are the Departmental Seminars and are supposed to be accessible to a general mathematics audience. They take place in room V/131, Vanbrugh College, at 4.00 pm. Tea will be available at 3.30 p.m. in the Senior Common Room, Vanbrugh College. 
The seminar slots on Mondays and Thursdays which are not filled by a regular seminar talk will be used for the
Dbrane reading seminar.
Programme
Please note that this is the tentative evolving program. It is advisable to recheck the page shortly before each talk. For further details or to be placed on the mailing list please contact
Dr. B.S. Kay or
Dr. G.W. Delius.
12 October Thursday 4.20pm  Phil Isaac (Brisbane) Quantum Lie Algebras This will be a generally accessible talk about quantum groups and quantum Lie algebras 
16 October Monday 4.20pm  Prof. John Roberts (Rome) Theory of Superselection Sectors 
30 October Monday 4.20pm  Brett Gibson (York) Boundary Breathers in the sineGordon model on the half line 
2 November Thursday 4.20pm  Dr Dirk Kreimer (Mainz) From the combinatorics of Feynman diagrams to running physical parameters 
8 November Wednesday 4pm  Cancelled because of flooding: Dr M Dritschel (NewcastleuponTyne) 
9 November Thursday 5:15pm room: V/045  Dr Chris Fewster (York) Open Lecture: A crash course in quantum mechanics This is part of a lecture series for nonscientists starting immediately after our usual seminar slot. 
15 November Wednesday 4pm  Dr Stephen Bramwall (University College London) Postponed because of flooding 
16 November Thursday 4:20pm  Dr Ruediger Schack (Royal Holloway) Postponed because of flooding 
20 November Monday 4:20pm  Dr Lucien Hardy (C.Q.C. Oxford) Can quantum theory be obtained from reasonable axioms? 
22 November Wednesday 4pm  Professor P C Chatwin (Sheffield) Aspects of the only unsolved problem of classical physics 
23 November Thursday 5:15pm room: V/045  Dr Chris Fewster (York) Open Lecture: Neither here nor there but both: the central mystery of quantum mechanics This is part of a lecture series for nonscientists starting immediately after our usual seminar slot. 
29 November Wednesday  Yorkshire Differential Geometry Day 
30 November Thursday 5:15pm V/045  Professor Tony Sudbery (York) Open Lecture: Putting weirdness to work: quantum information and quantum computing This is part of a lecture series for nonscientists starting immediately after our usual seminar slot. 
4 December Monday 4:20pm  Dr Michael Roesgen (Bonn) Applications of (essential) paths in conformal field theory 
6 December Wednesday 4pm  Dr James Vickers (Southampton) How to multiply distributions 
7 December Thursday 4:20pm  Dr Ruediger Schack (Royal Holloway) Generalized measurements and quantum Bayes rule 
11 December Monday 4:20pm  Dr David Rideout (Syracuse) A Stochastic Growth Dynamics for Causal Sets 
Autumn 1999
Mathematical Physics Seminars
Autumn 1999
We have two series of weekly Mathematical Physics seminars:
For further details or to be placed on the mailing list please contact
Dr. B.S. Kay or
Dr. G.W. Delius.
25 October:  5minute minitalks by F. Cornish, T. Brzezinski, E. Corrigan, G. Delius, C. Fewster, A. Higuchi, B. Kay, I. McIntosh, M. Nazarov, A. Sudbery. 
1 November:  Gustav Delius Conformal Field Theory I 
8 November:  Tomasz Brzezinski Algebraic Bethe Ansatz I 
15 November:  Gustav Delius Conformal Field Theory II 
22 November:  Tomasz Brzezinski Algebraic Bethe Ansatz II 
29 November:  Gustav Delius Conformal Field Theory III 
6 December:  Ed Corrigan The ADHM Construction I 
13 December:  Ed Corrigan The ADHM Construction II 
21 October:  Elizabeth Winstanley (Oxford) Black holes, infinite hair and antide Sitter space 
3 November:  free discussions 
11 November:  Maxim Nazarov (York) Reflection equation and classical Lie algebras 
18 November:  Christopher Fewster (York) A general quantum inequality 
25 November:  Tomasz Brzezinski (York) Algebraic Bethe Ansatz III: Solving the Bethe equations 
2 December:  Vadim Kuznetsov (Leeds) Bäcklund transformations for classical and quantum integrable systems 
9 December:  Nicholas Dorey (Swansea) title tba 
Lectures on Conformal Field Theory
Conformal Field Theory
I gave three introductory lectures on conformal field theory:
 In the first lecture I introduced complex coordinates and determined the twopoint function of the free boson in 2dimensional euclidean space as the simplest example of a conformal field theory.
 In the second lecture I introduced operators through the radial quantization procedure. We studied the energy momentum tensor of a free boson and derived the Virasoro algebra.
 In the third lecture (which was even less organised than the first two, sorry) we left the special example of the free boson and introduced the concept of primary conformal fields and their descendents. I indicated how correlation functions involving descendent fields are determined in terms of those of primary fields and finally I explained how the existence of null vectors in the Verma module generated by a primary field leads to differential equations for the correlation functions of the primary field
Obviously I only scratched the surface. I recommend the following for further reading:
The links point to a local copy of the scanned versions of the papers stored at KEK.
Gustav W Delius, 29/11/99