## 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)

### 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 hydrodynamics”. 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.

### 22.01.2020 (Wednesday)

#### Five-Point Functions in N=4 SYM

Regular Seminar Thiago Fleury (International Institute of Physics UFRN)

 at: 13:15 KCLroom S2.29 abstract: The correlation functions (three and higher point) in N=4 SYM can be computed using integrability techniques. One formalism is called hexagonalization and its main object is an integrable form-factor with hexagonal shape. It was successfully used to compute a specific all loop four-point function for the first time. However, it seems that new developments are needed to understand the five-point function and other kinds of finite size corrections. In this talk, after a long review of the hexagonalization procedure, I will explain the five-point calculation at weak coupling and its difficulties.

### 20.01.2020 (Monday)

#### Emergent diffusion and super-diffusion in quantum and classical chains.

Exceptional Seminar Jacopo de Nardis (University of Ghent)

 at: 13:00 KCLroom S5.20 abstract: Finding a theoretical framework to explain how phenomenological transport laws on macroscopic scales emerge from microscopic deterministic dynamics poses one of the most significant challenges of condensed matter physics. In recent years, the advent of the generalized hydrodynamics in integrable quantum systems and more recent studies of quantum chaos and its relation to transport, reinvigorated the field of nonequilibrium physics in spin chains. Numerous results were found: lower bounds to diffusion constants, exact expressions for diffusion coefficients and remarkable anomalous features of transport in quantum and classical chains, deeply related to the Kardar-Parisi-Zhang dynamical universality class. I will present an overview of such results with a particular focus on anomalous transport and its relation to non-linear hydrodynamics.

### 08.01.2020 (Wednesday)

#### TBA

Exceptional Seminar Eliezer Rabinovici (HUJ)

 at: 13:15 KCLroom K6.63 abstract: TBA

### 12.12.2019 (Thursday)

#### Thermodynamics of the XXZ spin-1/2 chain

Exceptional Seminar Salvish Goomanee (ENS Lyon)

 at: 11:00 KCLroom K4.31 abstract: In this talk I will present the novel developments pertaining the the thermodynamics of the XXZ spin-1/2 chain. I will describe the analysis allowing one to prove several features related to the behaviour of the Heisenberg-Ising (or XXZ) spin-1/2 chain at finite temperature. It has been argued in the literature that the per-site free energy or the correlation length admit integral representations whose integrands are expressed in terms of solutions of non-linear integral equations. The derivations of such representations rested on various unproven conjectures such as the existence of a real, non-degenerate, maximal in modulus Eigenvalue of the quantum transfer matrix, the existence and uniqueness of the solutions to the auxiliary non-linear integral equations in the infinite Trotter limit. I will show how these conjectures can be proven in a rigorous setting for temperatures high enough. The result of these analyses allowed one to observe that a subset of sub-dominant Eigenvalues of the quantum transfer matrix admits a large temperature asymptotic expansion.

### 11.12.2019 (Wednesday)

#### Asymptotic charges in gravity

 at: 13:15 KCLroom S2.29 abstract: I will review asymptotic charges in electromagnetism and explain why they are physical. Then I will review BMS charges in asymptotically flat spacetimes and show that there are in fact magnetic analogues of BMS charges that had been overlooked in the literature. I will comment on the implications of these newly found charges.

### 27.11.2019 (Wednesday)

#### Modularity of 3-manifold invariants

Regular Seminar Francesca Ferrari (SISSA)

 at: 13:15 KCLroom S2.29 abstract: Since the 1980s, the study of invariants of 3-dimensional manifolds has benefited from the connections between topology, physics and number theory. Recently, a new topological invariant has been discovered: the homological block (also known as the half-index of certain 3d N=2 theories). When the 3-manifold is a Seifert manifold given by a negative-definite plumbing the homological block turned out to be related to false theta functions and characters of logarithmic VOA's. In this talk I describe the role of quantum modular forms, false and mock theta functions in the study of the topology of 3-manifolds. The talk is based on the article 1809.10148 and work in progress with Cheng, Chun, Feigin, Gukov, and Harrison.

### 26.11.2019 (Tuesday)

#### Reflections and sum-rules for CFTs and modular forms

 at: 13:30 KCLroom K-1.56 abstract: In this talk, we discuss conformal field theories in two dimensions (2d CFTs) and aspects of the theory of modular forms. Physical considerations lead us to study two extensions to the theory of modular forms: modular forms for GL2(Z) that are defined on the double half-plane (in distinction to SL2(Z) modular forms defined on the upper half-plane), and L-functions for modular forms with poles *within* the fundamental domain. We introduce both concepts, and discuss their consistency, both with each other and with the physical considerations which led to them. Finally, we note that very similar physical considerations may apply to finite-temperature path integrals for generic QFTs in higher dimensions, and comment on possible consequences of this.

### 13.11.2019 (Wednesday)

#### Celestial primaries, soft limits and memory effects

Regular Seminar Andrea Puhm (CPHT, CNRS, Ecole polytechnique)

 at: 13:15 KCLroom S2.29 abstract: Novel insights into quantum gravity in asymptotically flat spacetimes evolving around soft theorems in scattering amplitudes, memory effects and asymptotic symmetries hint at an underlying holographic structure of Minkowski spacetime: information about 4D quantum gravity might be encoded in a 2D CFT on the celestial sphere at the conformal boundary of Minkowski spacetime. I will discuss recent progress on this attempted formulation of a flat space holography focusing on the 4D S-matrix which takes the form of a 2D correlator on the celestial sphere in a conformal basis. I will discuss how celestial conformal symmetry is generated by "conformally soft" gravitons and how insertions of the BMS supertranslation current in a correlator gives rise to the celestial analogue of Weinberg's soft graviton theorem.

### 06.11.2019 (Wednesday)

#### Soliton and breather gas in the focusing nonlinear Schrodinger equation

Regular Seminar Guennady El (Northumbria University)

 at: 13:15 KCLroom S2.29 abstract: Solitons and breathers are localized solutions of integrable systems that can be viewed as "particles'' of complex statistical objects called soliton and breather gases. In view of the growing evidence of their ubiquity in fluids and nonlinear optical media these integrable'' gases present fundamental interest for nonlinear physics. We develop nonlinear spectral theory of breather and soliton gases by considering a special, thermodynamic type limit of the nonlinear dispersion relations for multi-phase (finite-gap) solutions of the focusing nonlinear Schrödinger (fNLS) equation. A number of concrete examples of breather and soliton gases are considered, demonstrating efficacy of the developed general theory and also having some interesting implications. In particular, the statistical properties of a special kind of soliton gas, that we term the bound state soliton condensate, reveal a remarkable connection with the nonlinear stage of modulational instability. This is joint work with Alex Tovbis (Central Florida).

### 30.10.2019 (Wednesday)

#### Triangular Seminar at KCL: Event shapes and the light-ray OPE in CFTs

Triangular Seminar Alexander Zhiboedov (CERN)

 at: 15:00 KCLroom K2.31 Nash Lecture Theatre abstract: I will review recent progress in our understanding of light-ray operators in abstract CFTs. Light-ray operators first appeared in QCD and were later studied in N=4 Super Yang-Mills theory and holography by Hofman and Maldacena. More recently, they attracted new interest due to an important role played by the averaged null energy condition (ANEC) operator in various contexts. However, it is only during the last few years it became possible to start developing a more general theory of light-ray operators. I will explain a nonperturbative, convergent operator product expansion (OPE) for null-integrated operators on the same null plane in a CFT. I will discuss its application to energy-energy correlators in N=4 Super Yang-Mills theory.

### 30.10.2019 (Wednesday)

#### Triangular Seminar at KCL: From generalized global symmetries to pulsar magnetospheres

Triangular Seminar Nabil Iqbal (Durham University)

 at: 16:30 KCLroom K2.31 Nash Lecture Theatre abstract: Certain quantum field theories possess generalized global symmetries; just as ordinary global symmetries enforce the conversation of particle number, generalized global symmetries enforce the conservation of extended objects, such as strings. I will review this symmetry principle and argue that it governs the long-distance physics of conventional 4d electromagnetism, where the strings in question are magnetic field lines. I will then apply it to construct a novel effective theory for the description of strongly magnetized plasmas. One potential application of this new effective theory is to astrophysical pulsars, which are thought to be surrounded by strong magnetic fields as well as a high density of charged particles; the resulting zero temperature system is highly nonlinear. At leading order in derivatives our new effective theory agrees with the standard treatment in terms of force-free electrodynamics''. The inclusion of higher derivative terms however generically results in new and potentially observationally relevant effects, such as electric fields that accelerate charges to high energies along magnetic field lines. If time permits I will describe some recent work towards describing such energetic charges in terms of bosonization along magnetic field lines.