Found at least 20 result(s)

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 102608' style='color:#f0ad4e'>t Hooft loops and integrability

Regular Seminar Kostantin Zarembo (Nordita)

at:
01:00 - 01:00
KCL Strand
room: S0.12
abstract:

A ââ¬â¢t Hooft loop is a typical disorder operator defined in any gauge theory that can be studied by a combination of holography, localization and integrability. After reviewing the quantum mechanics magnetic monopoles, I will describe how integrability and Bethe ansatz can help to study ââ¬â¢t Hooft loops in the N=4 super-Yang-Mills theory.

Keywords:

01.01.1970 (Thursday)

ST' style='color:#f0ad4e'>ST 224' style='color:#f0ad4e'>Domain Selection for Gaussian Process Data: An application to Electrocardiogram Signals

regular seminar Nicolás Hernández (UCL)

at:
01:00 - 01:00
KCL, Strand
room: S5.20
abstract:

Gaussian Processes and the Kullback-Leibler divergence have been deeply studied in Statistics and Machine Learning. This paper marries these two concepts and introduce the local Kullback-Leibler divergence to learn about intervals where two Gaussian Processes differ the most. We address subtleties entailed in the estimation of local divergences and the corresponding interval of local maximum divergence as well. The estimation performance and the numerical efficiency of the proposed method are showcased via a Monte Carlo simulation study. In a medical research context, we assess the potential of the devised tools in the analysis of electrocardiogram signals.

Keywords: Statistics

01.01.1970 (Thursday)

AN' style='color:#f0ad4e'>AN 226' style='color:#f0ad4e'>Sharp estimates for conditionally centred moments and for compact operators on Lp spaces

regular seminar Eugene Shargorodsky (KCL)

at:
01:00 - 01:00
KCL, Strand
room: S5.20
abstract:

I will discuss sharp estimates for the norm of the operator âœidentity minus conditional expectationâ. They allow one to find the optimal constant in the bounded compact approximation property of Lp([0, 1]), 1 < p < infty. I will also discuss related open problems. The talk is based on a joint paper with T. Sharia.

Keywords:

01.01.1970 (Thursday)

GE' style='color:#f0ad4e'>GE 223' style='color:#f0ad4e'>Monodromy and mapping class groups of 3-dimensional hypersurfaces

regular seminar Oscar Randal-Williams (Cambridge University )

at:
01:00 - 01:00
KCL, Strand
room: S4.29
abstract:

Kreck and Su have recently described, almost completely, the mapping class group of a smooth hypersurface in CP^4. There is a "monodromy" map from the fundamental group of the space of all smooth hypersurfaces in CP^4 to this mapping class group, and I will explain how the image of this map can be described. I will then give some idea of the differential topology methods which go into the proof.

Keywords:

01.01.1970 (Thursday)

PR' style='color:#f0ad4e'>PR 193' style='color:#f0ad4e'>KCL Probability Seminar: Phase transition for the late points of random walk

regular seminar Perla Sousi (University of Cambridge)

at:
01:00 - 01:00
KCL, Strand
room: Strand Building S4.29
abstract:

Let X be a simple random walk in \mathbb{Z}_n^d with d\geq 3 and let t_{\rm{cov}} be the expected time it takes for X to visit all vertices of the torus. In joint work with Prévost and Rodriguez we study the set \mathcal{L}_\alpha of points that have not been visited by time \alpha t_{\rm{cov}} and prove that it exhibits a phase transition: there exists \alpha_* so that for all \alpha>\alpha_* and all \epsilon>0 there exists a coupling between \mathcal{L}_\alpha and two i.i.d. Bernoulli sets \mathcal{B}^{\pm} on the torus with parameters n^{-(a\pm\epsilon)d}with the property that \mathcal{B}^-\subseteq \mathcal{L}_\alpha\subseteq \mathcal{B}^+ with probability tending to 1 as n\to\infty. When \alpha\leq \alpha_*, we prove that there is no such coupling.

Keywords:

[tbc]

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 102581' style='color:#f0ad4e'>Lonti: Supergravity a la Fin de Siecle

Regular Seminar Neil Lambert (KCL)

at:
01:00 - 01:00
KCL Strand
room: LIMS
abstract:

In these lectures we will provide a basic introduction to Supergravity as it arises in String Theory and M-Theory. We will start by introducing vielbeins and spin connections in order to construct supergravity actions. In the second lecture we will briefly introduce the maximal supergravity theories in ten and eleven-dimensions. We will briefly discuss special holonomy manifolds, explicitly construct BPS p-brane solutions and prove their non-perturbative stability. Time permitting we will discuss toroidal compactifications and U-duality.

I will assume basic MSc level material (Riemannian geometry, fermions and rigid supersymmetry). The lecture notes that will be provided are largely self-contained but the text book ââ¬ÅSupergravityââ¬Â by Freedman and van Proeyen contains more details.

This time, there will be two lectures (one in the morning and one in the afternoon), with pizza lunch in between them.

Keywords:

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 202' style='color:#f0ad4e'>TBA

journal club Mann Jeremy (KCL)

at:
01:00 - 01:00
KCL, Strand
room: Norfolk Building 342N
abstract:

Keywords:

01.01.1970 (Thursday)

NT' style='color:#f0ad4e'>NT 212' style='color:#f0ad4e'>Internal number theory seminar: How common is formal complex multiplication?

regular seminar Alex Torzewski (KCL)

at:
01:00 - 01:00
KCL, Strand
room: K2.31
abstract:

An elliptic curve over a characteristic zero field is said to have complex multiplication when its endomorphism ring is larger than Z ("E has extra endomorphisms"). Generic elliptic curves don't have complex multiplication. Often one tries to understand elliptic curves via their Tate modules. When the Tate module of E has extra endomorphisms we say E has formal complex multiplication. Over a number field, E has formal complex multiplication if and only if it has complex multiplication. Over a local field this need not be the case. How often does this happen?

Keywords:

01.01.1970 (Thursday)

AN' style='color:#f0ad4e'>AN 199' style='color:#f0ad4e'>Plateau's problem via the theory of phase transitions

regular seminar Stephen Lynch (Imperial College London)

at:
01:00 - 01:00
KCL, Strand
room: S5.20
abstract:

Keywords:

Plateau's problem asks whether every boundary curve in 3-space is spanned by an area minimizing surface. Various interpretations of this problem have been solved using eg. geometric measure theory. Froehlich and Struwe proposed another approach, in which the desired surface is produced using smooth sections of a twisted line bundle over the complement of the boundary curve. The idea is to consider sections of this bundle which minimize an analogue of the Allen--Cahn functional (a classical model for phase transition phenomena) and show that these concentrate energy on a solution of Plateau's problem. After some background on the link between phase transition models and minimal surfaces, I will describe new work with Marco Guaraco in which we produce smooth solutions of Plateau's problem using this approach.

01.01.1970 (Thursday)

ME' style='color:#f0ad4e'>ME 206' style='color:#f0ad4e'>Maths education seminar: A variant on two-stage examination

regular seminar Jean Lagacé (King's College London)

at:
01:00 - 01:00
KCL, Strand
room: K0.50
abstract:

The two-stage examination method is a variant on exam taking whereby students are asked to take the same exam twice --- once in the 'usual' way, and the second time in small groups of three to four. It has been used in mathematics, physics and engineering since its inception 20 years ago at UBC in Vancouver, but is normally used in basic modules in the first or second year.

I will talk about a trial I am running on two-stage exams in a Masters level class. Here, the focus will be a bit different: I use the second part, in groups, to ask the students slightly more open-ended questions. In this talk I will talk about the concept, my observations, and the challenges that were faces in the first implementation.

Keywords:

01.01.1970 (Thursday)

GE' style='color:#f0ad4e'>GE 222' style='color:#f0ad4e'>Steklov eigenvalues of negatively curved manifolds

regular seminar Asma Hassannezhad (University of Bristol)

at:
01:00 - 01:00
KCL, Strand
room: S4.29
abstract:

The geometry and topology of negatively curved manifolds are subtly reflected in a geometric bound for the Laplace eigenvalues, a connection that has been explored since the 1980s. Building upon these foundational studies in the case of the Laplacian, we investigate the Steklov eigenvalues of pinched negatively curved manifolds with totally geodesic boundary. These eigenvalues are associated with a first-order elliptic pseudodifferential operator known as the Dirichlet-to-Neumann operator. We discuss how the results for Laplace eigenvalues can be extended to Steklov eigenvalues. In particular, we show a spectral gap for the Steklov eigenvalue problem in negatively curved manifolds with dimensions of at least three. This talk is based on joint work with Ara Basjmaian, Jade Brisson, and Antoine Métras.

Keywords:

01.01.1970 (Thursday)

PR' style='color:#f0ad4e'>PR 192' style='color:#f0ad4e'>KCL Probability Seminar: Solving spin systems â the Babylonian way.

regular seminar Nicola Kistler (Goethe-Universität Frankfurt)

at:
01:00 - 01:00
KCL, Strand
room: Strand Building S4.29
abstract:

The replica method, together with Parisi symmetry breaking mechanism, is a powerful tool which allows to compute the limiting free energy of virtually any mean field disordered system. Unfortunately, the tool is dramatically flawed from a mathematical point of view. I will discuss a truly elementary procedure which allows to rigorously implement two (out of three) steps of the procedure, and which allows to represent the free energy of virtually any model from statistical mechanics as a Gaussian mixture model. I will then conclude with some remarks on the ensuing Babylonian formulas and their relation with :
1) work by Dellacherie-Martinez-San Martin on M-matrices, potential theory and ultrametricity, the latter being the key yet unjustified assumption of the whole Parisi theory\DSEMIC
2) work of Mezard-Virasoro suggesting that the onset of scales and the universal hierarchical self-organisation of mean field random systems is intimately linked to hidden geometrical properties of large random matrices which satisfy rules reminiscent of the popular SUDOKU game.

Keywords: Replica method, Symmetry breaking

[tbc

01.01.1970 (Thursday)

DS' style='color:#f0ad4e'>DS 220' style='color:#f0ad4e'>Quantum Entanglement in Disordered Systems

regular seminar Prof. Leonid Pastur (KCL)

at:
01:00 - 01:00
KCL, Strand
room: S4.23
abstract:

Lecture 3 in the minicourse by Prof. Leonid Pastur

see

https://dsadvancedlectures.weebly.com/

Keywords:

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 102580' style='color:#f0ad4e'>Lonti: Supergravity a la Fin de Siecle

Regular Seminar Neil Lambert (KCL)

at:
01:00 - 01:00
KCL Strand
room: LIMS
abstract:

In these lectures we will provide a basic introduction to Supergravity as it arises in String Theory and M-Theory. We will start by introducing vielbeins and spin connections in order to construct supergravity actions. In the second lecture we will briefly introduce the maximal supergravity theories in ten and eleven-dimensions. We will briefly discuss special holonomy manifolds, explicitly construct BPS p-brane solutions and prove their non-perturbative stability. Time permitting we will discuss toroidal compactifications and U-duality.

I will assume basic MSc level material (Riemannian geometry, fermions and rigid supersymmetry). The lecture notes that will be provided are largely self-contained but the text book ââ¬ÅSupergravityââ¬Â by Freedman and van Proeyen contains more details.

Keywords:

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 211' style='color:#f0ad4e'>TBA

journal club Schaub Vladimir (KCL)

at:
01:00 - 01:00
KCL, Strand
room: Norfolk Building 342N
abstract:

Keywords:

01.01.1970 (Thursday)

ST' style='color:#f0ad4e'>ST 200' style='color:#f0ad4e'>Asynchronous development: novel experimental designs and applications of functional data analysis

regular seminar Daphne Ezer (University of York)

at:
01:00 - 01:00
KCL, Strand
room: S5.20
abstract:

Plants undergo several key developmental transitions, such as the decision to flower, that farmers would like to synchronise to maximise their yields. In this talk I will describe (i) a novel experimental design to understand how these transitions happen and (ii) a novel application of functional data analysis to help farmers breed more synchronised crops. To understand the biological regulation that leads to these transition points, a high temporal resolution of sampling would be required\DSEMIC however, the degree of developmental asynchrony makes such an experiment difficult to design. Instead, we sample a large collection of individual plants at the transition point and then estimate their age retroactively with a bootstrapping strategy, enabling us to order the plants along a pseudotime, giving us an unprecedented level of detail of the cascade of biological events that lead to the initiation of flowering. We then hypothesised that plants that are more sensitive to changes in day length (as occur in the spring and autumn) would have more synchronised development. Using functional data analysis approaches, we developed a predictive model of flowering synchrony on the basis of how the circadian rhythms of plants respond to changes in day length, in a population of plants with parents adapted from different latitudes. We are further adapting FDA methods to identify genetic loci that are significantly associated with these clock-related traits, which can be used to direct crop breeding for synchronised development.

Keywords:

01.01.1970 (Thursday)

AN' style='color:#f0ad4e'>AN 198' style='color:#f0ad4e'>Symmetrization inequalities on graphs

regular seminar Shubham Gupta (Imperial College London)

at:
01:00 - 01:00
KCL, Strand
room: S5.20
abstract:

In the Euclidean space setting, symmetrization inequalities is a classical theory that has been quite useful in solving problems coming from various parts of analysis: spectral geometry, variational problems, mathematical physics, spectral theory, to name a few. In my talk, I will discuss a possible extensions of this theory to the setting of graphs. It is a fairly new topic and most of the results in the area are proved in the last two years. I will talk about these developments, connections of this theory with discrete isoperimetric inequalities, and its possible applications to problems concerning 'analysis on graphs'. The talk will be at the interface of discrete math and analysis, and will be based on a joint work with Stefan Steinerberger.

Keywords:

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 102592' style='color:#f0ad4e'>QFT in AdS instead of LSZ

Regular Seminar Balt van Rees (Ecole Polytechnique)

at:
01:00 - 01:00
KCL Strand
room: S0.12
abstract:

The boundary correlation functions for a quantum field theory (QFT) in a fixed antiââ¬âœde Sitter (AdS) background should reduce to S-matrix elements in the flat-space limit. We consider this procedure in detail for four-point functions. With minimal assumptions we rigorously show that the resulting S-matrix element obeys a dispersion relation, the nonlinear unitarity conditions, and the Froissart-Martin bound. QFT in AdS thus provides an alternative route to fundamental QFT results that normally rely on the LSZ axioms.

Keywords:

01.01.1970 (Thursday)

ME' style='color:#f0ad4e'>ME 205' style='color:#f0ad4e'>Maths education seminar: The King's Factor

regular seminar Dr Asuka Kumon (King's College London)

at:
01:00 - 01:00
KCL, Strand
room: K0.50
abstract:

Keywords: Outreach

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 210' style='color:#f0ad4e'>Cohomogeneity-one Lagrangian Mean Curvature Flow

regular seminar Albert Wood (King's College London)

at:
01:00 - 01:00
KCL, Strand
room: S4.29
abstract:

Mean Curvature Flow, the negative gradient flow for the volume functional of submanifolds of Riemannian manifolds, is a well-studied field of modern geometric analysis. Of particular interest are classifications of self-similar solutions (shrinkers, expanders, and translators) and finite-time singularities\DSEMIC projects which when completed will hopefully allow one to apply the flow to prove results in Riemannian geometry and differential topology. Moreover, in a Calabi-Yau manifold the class of Lagrangian submanifolds is preserved by mean curvature flow, a fact which inspired Thomas and Yau to make influential conjectures about existence of special Lagrangians in Calabi-Yau manifolds.

In this talk, we aim to make progress towards an understanding of self-similar solutions and singularities of Lagrangian mean curvature flow, by focusing on Lagrangians in C^n that are cohomogeneity-one under the action of a compact Lie group. Interestingly, each such Lagrangian lies in a level set \mu^{-1}(c) of the moment map \mu, and mean curvature flow preserves this containment. Using this, we classify all shrinking, expanding, and translating solitons, and in the zero level set \mu^{-1}(0), we classify the Type I and Type II blowup models of LMCF singularities. Finally, given any special Lagrangian in \mu^{-1}(0), weâll show that it arises as a Type II blowup, thereby yielding infinitely many new singularity models of Lagrangian mean curvature flow.

The results presented in this talk are contained in the preprint â˜Cohomogeneity-One Lagrangian Mean Curvature Flowâ, which is jointly written with Jesse Madnick, University of Oregon.

Keywords: