Found at least 20 result(s)

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 102614' style='color:#f0ad4e'>Bootstrapping Smooth Line Operators in Chern-Simons-Matter CFTs

Regular Seminar De-liang Zhong (Imperial College, London)

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

We study Chern-Simons theories at large N with either bosonic or fermionic matter in the fundamental representation. We will show that for smooth conformal line operators, their spectrum and shape dependence can be effectively bootstrapped using minimal inputs.

Keywords:

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 240' style='color:#f0ad4e'>Physics/Maths event

regular seminar ()

at:
01:00 - 01:00
KCL, Strand
room: K2.31 (Nash Lecture Theatre)
abstract:

Keywords:

Internal Physics/Maths event, joint celebration of our research.

01.01.1970 (Thursday)

PR' style='color:#f0ad4e'>PR 245' style='color:#f0ad4e'>KCL Probability Seminar: Christmas lecture on the history of computational statistics and diffusion processes

regular seminar Nik Nsken (King's College London)

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

This talk will trace the development of computational statistics (and machine learning) from the inception of Markov Chain Monte Carlo in the 1940s at Los Alamos to the current advances in generative AI (see, e.g. https://deepai.org/machine-learning-model/text2img). The story is closely connected to the analysis of diffusion processes, and we will see interactions with neighbouring fields such as PDEs, stochastic analysis and geometry.

Keywords: Computational statistics, diffusion processes, machine learning, generative AI

n/a

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 221' style='color:#f0ad4e'>An Excursion into the String Spectrum

regular seminar Chrysoula Markou ()

at:
01:00 - 01:00
KCL, Strand
room: K0.20
abstract:

We propose a covariant technique to excavate physical bosonic string states by entire trajectories rather than individually. The approach is based on Howe duality: the strings spacetime
Lorentz algebra commutes with a certain inductive limit of sp(), with the Virasoro constraints
forming a subalgebra of the Howe dual algebra sp(). There are then infinitely many simple trajectories of states, which are lowestweight representations of sp() and hence of the Virasoro
algebra. Deeper trajectories are recurrences of the simple ones and can be probed by suitable
trajectoryshifting operators built out of the Howe dual algebra generators. We illustrate the formalism with a number of subleading trajectories and compute a sample of treelevel amplitudes.

Keywords:

01.01.1970 (Thursday)

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 251' style='color:#f0ad4e'>TBA

regular seminar Joseph Smith (KCL)

at:
01:00 - 01:00
KCL, Strand
room: Norfolk342N
abstract:

Keywords:

01.01.1970 (Thursday)

AN' style='color:#f0ad4e'>AN 250' style='color:#f0ad4e'>Exponential inequalities in probability spaces revisited

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-Russells 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:

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 102613' style='color:#f0ad4e'>Wilson Loop Duality and OPE for Form Factors of Half-BPS Operators

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:

01.01.1970 (Thursday)

DS' style='color:#f0ad4e'>DS 242' style='color:#f0ad4e'>Generative AI and Diffusion Models: a Statistical Physics Analysis (Part II)

regular seminar Biroli Giulio (cole Normale Suprieure 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:

01.01.1970 (Thursday)

GE' style='color:#f0ad4e'>GE 246' style='color:#f0ad4e'>Quiver mutations, Coxeter groups and hyperbolic manifolds

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:

01.01.1970 (Thursday)

PR' style='color:#f0ad4e'>PR 244' style='color:#f0ad4e'>KCL Probability Seminar: Fastest-Mixing Markov Chain on a Graph

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 inequality

n/a

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 102612' style='color:#f0ad4e'>Krylov perspective on Modular Hamiltonians and QCD.

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.

Keywords:

01.01.1970 (Thursday)

DS' style='color:#f0ad4e'>DS 241' style='color:#f0ad4e'>Generative AI and Diffusion Models: a Statistical Physics Analysis (Part I)

regular seminar Biroli Giulio (cole Normale Suprieure 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.

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 247' style='color:#f0ad4e'>TBA

journal club William Pannell (KCL)

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

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01.01.1970 (Thursday)

NT' style='color:#f0ad4e'>NT 213' style='color:#f0ad4e'>Internal number theory seminar: Explicit local solubility in families of varieties

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:

01.01.1970 (Thursday)

ST' style='color:#f0ad4e'>ST 239' style='color:#f0ad4e'>Annealed Sequential Monte Carlo Samplers

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.

In this talk, we intend to describe all the components of an SMCS algorithm and their influence on the variance of the normalizing constant. Specifically, we will demonstrate that SMCS exhibits fundamentally different behaviour in large particle and dense schedule limits. The dense schedule limit reveals the natural geometry induced by annealing, which can pinpoint optimal performance and tune the number of particles, number of annealing distributions, annealing schedules, the resampling schedule, and the path. Lastly, we propose an efficient, black-box algorithm for tuning SMCS that delivers optimal performance within a fixed, user-specified computation budget, all while preserving the unbiasedness of the normalizing constant.

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01.01.1970 (Thursday)

AN' style='color:#f0ad4e'>AN 248' style='color:#f0ad4e'>Fokas Diagonalization

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:

01.01.1970 (Thursday)

TP' style='color:#f0ad4e'>TP 102611' style='color:#f0ad4e'>Harmonic analysis and the conformal bootstrap reloaded

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.

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01.01.1970 (Thursday)

ME' style='color:#f0ad4e'>ME 218' style='color:#f0ad4e'>Maths education seminar: Effective practice in mathematical outreach

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:

01.01.1970 (Thursday)

GE' style='color:#f0ad4e'>GE 243' style='color:#f0ad4e'>Knots, minimal surfaces and J-holomorphic curves

regular seminar Joel Fine (Universit 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.

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