Found at least 20 result(s)
regular seminar Esther Bou Dagher (Imperial College London)
at: 01:00 - 01:00 KCL, Strand room: S5.20 abstract: | In this talk, we revisit several results on exponential integrability in probability spaces and derive some new ones. In particular, we give a quantitative form of recent results by Cianchi, Musil, and Pick in the framework of Moser-Trudinger-type inequalities, and recover Ivanisvili-Russell’s inequality for the Gaussian measure. One key ingredient is the use of a dual argument, which is new in this context, that we also implement in the discrete setting of the Poisson measure on integers. This is a joint work with Ali Barki, Sergey Bobkov, and Cyril Roberto. Keywords: |
Regular Seminar Benjamin Basso (LPENS, Paris)
at: 01:00 - 01:00 KCL Strand room: S0.12 abstract: | I will explain how to describe form factors of single-trace half-BPS operators in planar N=4 super Yang Mills theory using the T-dual Wilson loop picture. After reviewing earlier results for operators in the stress-tensor multiplet, I will present the dual Wilson loop description for the so-called MHV form factors of half-BPS operators. The general proposal relates these form factors to the matrix elements of a null periodic super Wilson loop with outgoing states composed of zero-momentum scalars. I will present perturbative tests of this description at weak coupling. I will then explain how to obtain exact result at finite coupling in the collinear limit using the Wilson loop Operator Product Expansion. I will conclude with general comments and speculations about form factors of unprotected operators such as the Konishi operator. Keywords: |
regular seminar Biroli Giulio (École Normale Supérieure de Paris)
at: 01:00 - 01:00 KCL, Strand room: S4.23 abstract: | Part II. A statistical physics analysis using random matrix theory and mean-field methods. Keywords: |
regular seminar Pavel Tumarkin (Durham University)
at: 01:00 - 01:00 KCL, Strand room: S-2.25 abstract: | Mutations of quivers were introduced by Fomin and Zelevinsky in the context of cluster algebras. Since then, mutations appear (sometimes completely unexpectedly) in various domains of mathematics and physics. Using mutations of quivers, Barot and Marsh constructed a series of presentations of finite Coxeter groups as quotients of infinite Coxeter groups. I will discuss a geometric interpretation of this construction: these presentations give rise to a construction of geometric manifolds with large symmetry groups, in particular to some hyperbolic manifolds of relatively small volume with proper actions of Coxeter groups. If time permits, I will discuss a generalization of the construction of Barot and Marsh leading to a new invariant of bordered marked surfaces, and relation to extended affine Weyl groups. The talk is based on joint works with Anna Felikson, John Lawson and Michael Shapiro. Keywords: |
regular seminar Sam Olesker-Taylor (University of Warwick)
at: 01:00 - 01:00 KCL, Strand room: S4.29 abstract: | Given a graph G = (V,E), consider the set of all discrete-time, reversible Markov chains with equilibrium distribution uniform on V and transitions only across edges E of the graph. We establish a Cheeger-type inequality for the fastest mixing time using the vertex conductance of G. We also consider chains with almost-uniform invariant distribution. Time permitting, we also discuss a construction of a continuous-time chain with exactly-uniform invariant distribution and average jump-rate 1, and mixing time bounded by the d^2 log(n), where d is the graph diameter and n is the number of vertices. Keywords: Markov chain, mixing time, Cheeger inequalityn/a |
Exceptional Seminar Pawel Caputa (U. Warsaw)
at: 01:00 - 01:00 KCL Strand room: BH NE -1.01 abstract: | I will discuss some of the recent developments in the Krylov complexity. In particular, I will focus on the applications of the Krylov basis techniques to the modular Hamiltonian evolution and I will discuss a new angle on entanglement entropy in QCD at high energies. Based on arXiv:2306.14732 [hep-th] and work in progress.
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regular seminar Biroli Giulio (École Normale Supérieure de Paris)
at: 01:00 - 01:00 KCL, Strand room: S4.23 abstract: | Part I, Introduction and theoretical basis: how time-reversing Langevin dynamics one can create images from white noise. Keywords:Distinguished Visitor Series at KCL. First part of a mini-course. |
journal club William Pannell (KCL)
at: 01:00 - 01:00 KCL, Strand room: Norfolk 342 N abstract: | Keywords: |
regular seminar Chris Keyes (KCL)
at: 01:00 - 01:00 KCL, Strand room: K0.50 abstract: | How often does a randomly chosen variety have a point? Answering this question depends on the family of varieties in question, how we decide to order them, and what kinds of points we are looking for. Motivated by rational points, we endeavor to explicitly describe how often a randomly chosen variety is everywhere locally soluble. When our family is described by the fibers of a suitable morphism, this likelihood is equal to the product of local probabilities at each place and in some cases may be computed exactly. In particular, in joint work with Lea Beneish we find that for almost 97% of integral binary sextic forms f(x,z), the superelliptic curve y^3 = f(x,z) is everywhere locally soluble, with the local factors described explicitly by rational functions. Time permitting, we will discuss ongoing work on determining how often a cubic hypersurface has a rational point. Keywords: |
regular seminar Saifuddin Syed (University of Oxford)
at: 01:00 - 01:00 KCL, Strand room: S5.20 abstract: | Sequential Monte Carlo Samplers (SMCS) constitute a widely used class of SMC algorithms that calculate normalizing constants and simulate complex multi-modal target distributions. Typically, SMCS utilizes a process known as annealing, which propagates solutions from a tractable reference distribution to the intractable target through a continuous path of increasingly complex distributions. SMCS delivers state-of-the-art performance when adequately tuned, although this can pose a challenge for current tuning methods, yielding a random run-time and compromising the normalizing constant's unbiasedness.
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regular seminar Dave Smith ( Yale-NUS College)
at: 01:00 - 01:00 KCL, Strand room: S5.20 abstract: | We describe a new form of diagonalization for linear two point constant coefficient differential operators with arbitrary linear boundary conditions. Although the diagonalization is in a weaker sense than that usually employed to solve initial boundary value problems (IBVP), we show that it is sufficient to solve IBVP whose spatial parts are described by such operators. We argue that the method described may be viewed as a reimplementation of the Fokas transform method for linear evolution equations on the finite interval. The results are extended to multipoint and interface operators, including operators defined on networks of finite intervals, in which the coefficients of the differential operator may vary between subintervals, and arbitrary interface and boundary conditions may be imposed\DSEMIC differential operators with piecewise constant coefficients are thus included. Keywords: |
Regular Seminar Dalimil Mazac (IPhT, Saclay)
at: 01:00 - 01:00 KCL Strand room: S0.12 abstract: | I will discuss a connection between harmonic analysis on hyperbolic n-manifolds and conformal field theory in n-1 dimensions. Used in one direction, this connection leads to new spectral bounds on hyperbolic manifolds. Used in the other direction, it offers a new viewpoint on the spectra data of conformal field theories. Keywords: |
regular seminar Peter Rowlett (Sheffield Hallam University)
at: 01:00 - 01:00 KCL, Strand room: K0.50 abstract: | There are many ways to engage with mathematics, and therefore many different forms of maths engagement aimed at different audiences. A brief survey will present a range of different practices and encourage thought about target audience. We'll consider how to design effective outreach, and how informal engagement with maths before university can influence the decision to study maths at university. From a practical point of view, I will describe a programme of maths engagement for secondary school students implemented in local schools and on campus. Keywords: |
regular seminar Joel Fine (Université Libre de Bruxelles)
at: 01:00 - 01:00 KCL, Strand room: S4.29 abstract: | Let $K$ be a knot or link in the 3-sphere, thought of as the ideal boundary of hyperbolic 4-space $\mathbb{H}^4$. I will describe a programme to count minimal surfaces in $\mathbb{H}^4$ which have $K$ as their asymptotic boundary. This should give an isotopy invariant of the knot. I will explain what has been proved and what remains to be done. Minimal surfaces correspond to $J$-holomorphic curves in the twistor space $Z\to\mathbb{H}^4$, and so this invariant can be seen as a Gromov-Witten type invariant of $Z$. The big difference with the “standard†situation is that the almost complex structure on $Z$ (equivalently, the metric on $\mathbb{H}^4$) blows up at the boundary. This means the $J$-holomorphic equation, or minimal surface equation, becomes degenerate at the boundary of the domain. As a consequence, both the Fredholm and compactness parts of the story need to be reworked by hand. If there is time I will explain how this can be done, relying on results of Mazzeo-Melrose from the 0-calculus, and also some results from the theory of minimal surfaces. Keywords: |
regular seminar Adam Jakubowski (Nicolaus Copernicus University in Torun)
at: 01:00 - 01:00 KCL, Strand room: S4.29 abstract: | In 1953 Yu. Prohorov published a paper on weak convergence of
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journal club Andrew Svesko (KCL)
at: 01:00 - 01:00 KCL, Strand room: Norfolk Building 342N abstract: | Keywords: |
Regular Seminar Pau Figueras (QMUL)
at: 01:00 - 01:00 KCL Strand room: LIMS abstract: | In these series of lectures we will explore initial value problem in general relativity and how it can be solved in a computer in practical situations. We will first cover the necessary mathematical foundations, including the concepts of well-posedness and strong hyperbolicity, and then explore the current formulations of Einstein’s theory of gravity that are implemented in modern numerical codes, namely generalised harmonic coordinates and the BSSN formulation. We shall see how the latter can be implemented in a toy code so as to get some hands on experience. Time permitting, we will also explore the initial boundary value problem in asymptotically anti-de Sitter spaces and how it can be solved in practice using the characteristic formulation of the Einstein equations in applications of holography. Keywords: |
regular seminar Michael Levitin (University of Reading)
at: 01:00 - 01:00 KCL, Strand room: S5.20 abstract: | I will discuss a recent progress on two classical problems. The first one comes mostly from applied mathematics and numerical analysis: find tight universal and preferably simple enclosures for zeros of Bessel functions, of their derivatives, and possibly of other special functions. The second one comes primarily from number theory: find bounds for the number of lattice points under the graph of a given function (with some restrictions on the class of functions). As an application of these results, I’ll show the validity of inequalities à la Pólya for the magnetic Aharonov--Bohm Laplacian in the disk, discuss possible generalisations, and open problems. The talk covers some joint works, mostly in progress, with N. Filonov, I. Polterovich, and D. A. Sher. Keywords: |
Regular Seminar Anatoly Konechny (Heriot-Watt)
at: 01:00 - 01:00 KCL Strand room: S0.12 abstract: | We will consider perturbations of 2D CFTs by multiple relevant operators. The massive phases of such perturbations can be labeled by conformal boundary conditions. Cardy's variational ansatz approximates the vacuum state of the perturbed theory by a smeared conformal boundary state. In this talk we will discuss the limitations and propose generalisations of this ansatz using both analytic and numerical insights based on TCSA.
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regular seminar Dan Abramson (King's College London)
at: 01:00 - 01:00 KCL, Strand room: K0.50 abstract: | King's College London Mathematics School is for students aged 16-18 with an enthusiasm and aptitude for mathematics, and aims to widen participation in high-quality degrees and careers in the mathematical sciences.
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