## Directions

This institute may be found at Strand in Central London, just north of the Thames (map).

Getting to the Strand Campus:

• #### By underground

Temple (District and Circle lines): 2 minute walk. Charing Cross (Bakerloo and Northern lines): 10 minute walk, Embankment (District, Circle and Bakerloo lines): 10 minute walk, Waterloo (Jubilee, Northern, Bakerloo, Waterloo & City lines): 12 minute walk, Holborn (Central and Picadilly lines): 12 minute walk,Chancery Lane (Central line): use exit 4 - 15 minute walk.

• #### By train

Charing Cross: 9 minute walk. Waterloo: 12 minute walk. Waterloo East: 10 minute walk. Blackfriars: 12 minute walk.

• #### By bus

Buses stopping outside the College: 1, 4, 26, 59, 68, 76, X68, 168, 171, 172, 176(24 hour), 188, 243 (24 hour), 341 (24 hour), 521, RV1.

## Seminars at King's College London

Found at least 20 result(s)

### 30.11.2020 (Monday)

#### Lonti: Conformal blocks in two dimensions

Regular Seminar Gerard Watts (KCL)

 at: 10:30 KCLroom Online abstract: This is the live session included as part of the LonTI lecture on Conformal blocks in two dimensions. Please register at https://lonti.weebly.com/registration.html to receive joining instructions for this live session which will be held via Zoom.â€‹â€‹Conformal blocks are the building blocks of conformal field theories, the key ingredients of correlation functions and knowledge of these blocks is central to the conformal bootstrap. This lecture covers some general results before quickly specialising to two-dimensions. It discusses the implications of global conformal invariance and then the larger and more constraining Virasoro algebra symmetry. It introduces various methods of calculation including brute force, differential equations, recursion relations and closed formulae - and some aspects of bootstrap techniques.

### 25.11.2020 (Wednesday)

#### Multilegs, Superfluids and Semiclassics

Regular Seminar Riccardo Rattazzi (EPFL)

 at: 13:15 KCLroom Zoom abstract: Even in weakly coupled QFTs, perturbation theory breaks down when one considers amplitudes with a large number $n$ of legs. The series cleverly organizes as a double expansion in $g^2$ and $g^2n$. I show how the series in $g^2n$ can be fully captured by a semiclassical expansion around a non-trivial solution. Focussing on $U(1)$ symmetric $|\phi|^4$ theory in $4$ and $4-\epsilon$ dimension, I derive explicit and consistent all order results for the anomalous dimension of the complex operator $\phi^n$. When restricting to the Wilson-Fisher fixed point and working on the cylinder, the dominant trajectory is seen to correspond to a superfluid phase for the conserved U(1). This creates a correspondence between, on one side, the spectrum of operators and fusion coefficients and and on the other the spectrum of hydrodynamics modes and their interactions. The results also nicely match Monte Carlo simulations in 3D, compatibly with the stunt of taking $\epsilon=1$. [please email alejandro.cabo_bizet@kcl.ac.uk for the Zoom link]

### 24.11.2020 (Tuesday)

Colloquium Matthias Gaberdiel (ETH Zurich)

 at: 14:30 KCLroom Zoom abstract: The AdS/CFT correspondence relates string theory on an Anti de Sitter (AdS) background to a dual conformal field theory (CFT) living on the boundary of AdS. One promising strategy for how to prove the duality is to consider the tensionless' limit of string theory in which the dual CFT becomes weakly coupled. For the case of string theory on AdS3 we have recently identified a solvable world-sheet description for this tensionless limit. This opens the way towards proving the AdS/CFT correspondence, at least for this specific set-up. Please contact Dionysios Anninos (dionysios.anninos@kcl.ac.uk) for the zoom link.

### 23.11.2020 (Monday)

#### Lonti 2020: Conformal blocks in two dimensions

Regular Seminar Gerard Watts (KCL)

 at: 14:00 KCLroom Youtube abstract: â€‹â€‹Conformal blocks are the building blocks of conformal field theories, the key ingredients of correlation functions and knowledge of these blocks is central to the conformal bootstrap. This lecture covers some general results before quickly specialising to two-dimensions. It discusses the implications of global conformal invariance and then the larger and more constraining Virasoro algebra symmetry. It introduces various methods of calculation including brute force, differential equations, recursion relations and closed formulae - and some aspects of bootstrap techniques.

### 18.11.2020 (Wednesday)

#### Universes as Bigdata: from Geometry, to Physics, to Machine-Learning

Polygon Seminar Yang-Hui He (City)

 at: 13:00 KCLroom Online abstract: We briefly overview how historically string theory led theoretical physics first to algebraic/differential geometry, and then to computational geometry, and now to data science. Using the Calabi-Yau landscape - accumulated by the collaboration of physicists, mathematicians and computer scientists over the last 4 decades - as a starting-point and concrete playground, we then launch to review our recent programme in machine-learning mathematical structures and address the tantalizing question of how AI helps doing mathematics, ranging from geometry, to representation theory, to combinatorics, to number theory. Zoom Link: https://us02web.zoom.us/j/83496714171?pwd=bld3QmQ2c21laWxEWTd6ejVQbjZ5dz09 (contact dionysios.anninos@kcl.ac.uk for password)

### 11.11.2020 (Wednesday)

#### The large charge expansion

Regular Seminar Susanne Reffert (University of Bern)

 at: 13:45 KCLroom Zoom, See abstract. abstract: In has become clear in recent years that working in sectors of large global charge of strongly coupled and otherwise inaccessible CFTs leads to important simplifications. It is indeed possible to formulate an effective action in which the large charge appears as a control parameter. In this talk, I will explain the basic notions of the large-charge expansion using the simple example of the O(2) model and then generalize to models with a richer structure which showcase other effects. [For the zoom link please email alejandro.cabo_bizet@kcl.ac.uk]

### 04.11.2020 (Wednesday)

#### Type-B Anomalies on the Higgs Branch

Regular Seminar Elli Pomoni (DESY)

 at: 13:45 KCLroom Zoom, see abstract abstract: In this talk we will study type-B conformal anomalies associated with 1/2-BPS Coulomb-branch operators in 4D N=2 SCFTs. We will derive the conditions under which these anomalies can match across the conformal phase and the Higgs phase, and explicitly see them at work in concrete examples of both matching and non-matching. On the one hand matching leads to a new class of data on the Higgs branch of 4D N=2 SCFTs that are exactly computable. On the other, non-matching imposes novel restrictions on the holonomy of the conformal manifold. [For the Zoom link, please email to: alejandro.cabo_bizet@kcl.ac.uk ]

### 23.10.2020 (Friday)

#### Renormalons from Resurgence

Informal Seminar Tomas Reis (University of Geneva)

 at: 13:00 KCLroom Zoom, See abstract abstract: In this talk I will present the use of resurgence techniques in identifying non-perturbation physics and its relation to renormalons, in light of recent work of Marcos MariÃ±o and me. This exploration has touched 1+1 QFTs and condensed matter systems, revealing that the presence of renormalons is more widespread than expected. After introducing both ideas in the title, I will specialise in the case of the 1D fermion gas with dirac-delta attractive potential. This case is a clean example of our approach and unveils a curious interplay between resurgence, renormalons, and superconductivity. [Please email damian.galante@klc.ac.uk for the link]

### 21.10.2020 (Wednesday)

#### Liouville and JT quantum gravity - holography and matrix models

Regular Seminar Thomas Mertens (GENT U.)

 at: 13:15 KCLroom Zoom abstract: In this talk, we will discuss recent progress in understanding quantum gravity amplitudes (partition function and boundary correlation functions) in Liouville gravity, and how they limit to Jackiw-Teitelboim (JT) correlators. We also discuss multiboundary and higher genus amplitudes. We focus on two main results: the Liouville gravity answers look like q-deformations of the JT answers, and Liouville gravity can be related to a 2d dilaton gravity with a sinh dilaton potential. We end with discussions on supersymmetric extensions and work in progress. Based largely on arXiv:2006.07072 and 2007.00998â€‹. [For the Zoom link, please email to: alejandro.cabo_bizet@kcl.ac.uk ]

### 07.10.2020 (Wednesday)

#### The butterfly effect away from maximal chaos

Regular Seminar Gabor Sarosi (CERN)

 at: 13:15 KCLroom Zoom abstract: A simple probe of chaos and operator growth in many-body quantum systems is the thermal out of time ordered (OTO) four point function. In a large class of local systems, the effects of chaos in this correlator build up exponentially fast inside a so called butterfly cone. I will discuss universal features of the spatiotemporal structure of this exponential growth in large N systems. In particular I will argue that there can be a smaller, â€œscramblonâ€ cone inside the butterfly cone. Outside the scramblon cone, the growth of the OTO four point function is completely universal and saturates a chaos bound. I will explain the connection to conformal Regge theory, where crossing the scramblon cone is related to an exchange of dominance between the pomeron and the stress tensor. Finally, I will discuss a connection between chaos and energy transport, called the pole skipping phenomenon, which is a subtle effect in the thermal energy density retarded two point function at a special point in the complex frequency and momentum planes. I will present an improved understanding of this connection and test it in the large q limit of an SYK chain, where I determine both the Lyapunov growth of the OTO correlator and the energy density two point function exactly as a function of the coupling, interpolating between weekly coupled and maximally chaotic behaviour. [For the Zoom link, please email to: alejandro.cabo_bizet@kcl.ac.uk ]

### 30.09.2020 (Wednesday)

#### Lorentzian CFT 3-point functions and the ANEC

Regular Seminar Teresa Bautista Solans (KCL)

 at: 13:15 KCLroom Zoom, see abstract abstract: In CFT, the expressions for Euclidean 3-point functions in momentum space were fully obtained in recent years, but their Lorentzian counterparts have remained quite unknown. In this talk I will present the expression for the Lorentzian 3-point function of scalars, and further show a way to obtain tensorial ones. As I will argue, such momentum-space expressions simplify considerably the computation of the expectation values of the ANEC (Average Null Energy Condition) operator on the states used in the conformal colliders setting, whose positivity has been used to put interesting bounds on conformal anomalies. With the motivation of generalising these bounds and studying the implications of the ANEC for QFT, I will discuss perturbative corrections to the simplest ANEC expectation values in lambda-phi4 theory. [For the Zoom link, please email to: alejandro.cabo_bizet@kcl.ac.uk ]

### 27.05.2020 (Wednesday)

#### Higher-derivative supergravity for AdS4 holography

Regular Seminar Kiril Hristov (INRNE, Bulgarian Academy of Sciences)

 at: 13:15 KCLroom See abstract abstract: In this talk I discuss some work in progress concerning higher-derivative (HD) terms in 4d supergravity. In particular we'll focus on the simplest case of 4-derivative terms appearing in minimal gauged supergravity. This choice minimizes the freedom in the HD terms to two arbitrary constants, which can be determined by a holographic match. This gives a prediction about the reduction of 11d HD terms on S^7. We then derive holographic predictions for the first subleading terms of various supersymmetric partition functions in their expansion of the gauge group rank, N. Additionally we are able to evaluate the on-shell action for non-BPS solutions in supergravity, allowing us to discuss black hole thermodynamics in the presence of HD terms. (To request the Zoom link send email with empty text and subject "talk" to alejandro.cabo_bizet@kcl.ac.uk)

### 03.04.2020 (Friday)

#### Recovering the spacetime metric from a holographic dual

Journal Club Leonel Quinta Queimada (King's College London)

 at: 13:00 KCLroom Virtual abstract: I will try to provide an overview of the papers 1605.01070, 1612.00391 and most recently 2003.08409, where progress is made in determining how the bulk metric of a holographic spacetime can be reconstructed purely from boundary data. My focus will be in the results of the first reference 1605.01070, which provides the framework for the other works. Link to meeting: here

### 27.03.2020 (Friday)

#### Toward an Effective CFT2 from N = 4 Super Yang-Mills and Aspects of Hawking Radiation

Journal Club Alejandro Cabo-Bizet (KCL)

 at: 13:00 KCLroom Virtual abstract: I will discuss the recent paper 2003.02770 with the title above (by J. Nian and L. Pando Zayas). Link to meeting: here

### 25.03.2020 (Wednesday)

#### TBA

Regular Seminar Agnese Bissi (Uppsala University)

 at: 13:15 KCLroom S2.29 abstract: TBA

### 20.03.2020 (Friday)

#### Emergent hydrodynamics in integrable systems

Journal Club Benjamin Doyon (King's College London)

 at: 13:00 KCLroom Virtual abstract: Join here (you need Microsoft Teams). Typical systems of many particles in strong interaction have extremely complex behaviours which are hard to study in detail. But when the system is very large, simplicity resurfaces: typically just a few degrees of freedom are relevant, which follow new, simple laws. Understanding what the emergent behaviours are from the underlying microscopic interactions is one of the foremost problems in modern science. A very powerful set of ideas and tools at our disposal is hydrodynamics. Although the Navier-Stokes and related equations have been studied for a very long time, we are now starting to uncover the full potential of the fundamental principles of hydrodynamics. In particular, in a recent breakthrough it was understood how to apply these principles to quantum and classical integrable models, where infinitely many conserved currents exist, giving `generalised hydrodynamicsâ€. I will overview the fundamental principles of hydrodynamics and their adaptation to integrable systems, with simple examples such as the quantum Lieb-Liniger model, the classical Toda model, and the soliton gases. I will discuss a recent cold-atom experiment that confirmed generalised hydrodynamics, and, if time permits, show some of the exact results that can be obtained with this formalism, such as exact nonequilibrium steady states and exact asymptotic of correlation functions at large space-time separations.

### 26.02.2020 (Wednesday)

#### Color Confinement, Bose-Einstein Condensation and Holographic Emergent Space

Regular Seminar Masanori Hanada (Southampton U.)

 at: 13:15 KCLroom S2.29 abstract: We propose a unified description of two important phenomena: color confinement in large-$N$ gauge theory, and Bose-Einstein condensation (BEC). The key lies in relating standard criteria, based on off-diagonal long range order (ODLRO) for BEC and the Polyakov loop for gauge theory: the constant offset of the distribution of the phases of the Polyakov loop corresponds to ODLRO. Indistinguishability associated with the symmetry group --- SU(N) or O(N) in gauge theory, and S_N permutations in the system of identical bosons --- is crucial in either case. This viewpoint may have implications for confinement at finite N, and for quantum gravity via gauge/gravity duality. As a byproduct, we obtain a characterization of the partially-confined/partially-deconfined phase at finite coupling: the constant offset of the distribution of the phases of the Polyakov loop is the order parameter.

### 19.02.2020 (Wednesday)

#### Polygon Seminar KCL: Symmetries and energy in general relativity

Polygon Seminar Mahdi Godazgar (QMUL)

 at: 14:00 KCLroom STRAND S -1.04 abstract: I will review the relation between symmetries and charges and explain how this works in the context of gravity. I will then explain how dual charges can be derived from a similar procedure.

### 12.02.2020 (Wednesday)

#### Amplitudes meet Cosmology

Regular Seminar Paolo Benincasa (NBI)

 at: 13:15 KCLroom S2.29 abstract: The principles of Lorentz invariance, locality and unitarity highly constrain the physics at accessible high energy: the type of interactions allowed as well as most of the theorems known in particle physics are instances of these principles. This is neatly seen in the structure of scattering amplitudes in asymptotically flat space-times. However, cosmology suggests that such principles may be just approximate: Lorentz invariance is broken at cosmological scales and the accelerated expansion of the universe seems to prevent a full-fledge definition of quantum mechanical observables. If our fundamental ideas in particle physics become somehow approximate in cosmology, what are the fundamental rules governing cosmological processes? In this talk I will report on a recent program which aims to address this question, by bringing both philosophy and methods which have been successful for scattering amplitudes to the analysis of cosmological observables. In particular we investigate the analytic properties of the perturbative wavefunction of the universe, how fundamental physics is encoded into it, how the flat-space physics reflects into it, and how all these features are encoded into new mathematical structures, which can be used as a novel first principle definition of the perturbative wavefunction.

### 29.01.2020 (Wednesday)

#### The O(N) S-matrix monolith

Regular Seminar Lucia Cordova (ENS, Paris)

 at: 13:15 KCLroom S2.29 abstract: In this talk I will explore the space of two-to-two S-matrices in two-dimensional theories with a global O(N) symmetry, as restricted by the general principles of unitarity, crossing and analyticity. I will describe various features of the allowed space and identify some special points on its boundary with known integrable theories. Finally, I will present a useful dual formulation of the S-matrix bootstrap problem. Based on arXiv:1909.06495.