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.

For more information about public transportations in London, please visit http://www.tfl.gov.uk.

Seminars at King's College London

Found at least 20 result(s)

20.02.2019 (Wednesday)

Witten, Cardy, and the Holonomy Saddle

Regular Seminar Piljin Yi (KIAS)

at:
13:15 KCL
room S2.49
abstract:

This talk will explore topological invariants of susy gauge theories, with some emphasis on index-like quantities and the notion of holonomy saddles. We start with 1d refined Witten index computations where the twisted partition functions typically show rational, rather than integral, behavior. We will explain how this oddity is a blessing in disguise and propose a universal tool for extracting the truely enumerative Witten indices. In part, this finally put to the rest a two-decade-old bound state problems which had originated from the M-theory hypothesis. Along the way, we resolve an old and critical conflict between Kac+Smilga and Staudacher/Pestun, circa 1999~2002, whereby the notion of holonomy saddles emerges and plays a crucial role. More importantly, the holonomy saddle prove to be universal features of supersymmetric gauge theories when the spacetime include a small circle. We explore them further for d=4, N=1 theories, with much ramifications on recent claims on Cardy exponents of their partition functions.

30.01.2019 (Wednesday)

Cosmic censorship violation and black hole collisions in higher dimensions

Regular Seminar Roberto Emparan (ICREA, Barcelona)

at:
13:15 KCL
room S2.49
abstract:

The cosmic censorship conjecture raises the question of whether classical gravitational dynamics can drive a low-energy configuration into an accessible regime of quantum gravity, with Planck-scale curvatures and energy densities visible by distant observers. I will present evidence that cosmic censorhip is violated in the quintessential phenomenon of General Relativity: the collision and merger of two black holes. It only requires a sufficient total angular momentum in a collision in high enough number of dimensions. Nevertheless, I will argue that even if cosmic censorship is violated in this and in some other know instances, its spirit remains unchallenged: classical relativity describes the physics seen by observers outside the black holes accurately, with only minimal quantum input that does not entail macroscopic disruptions.

23.01.2019 (Wednesday)

What spatial geometry does the (2+1)-d QFT vacuum prefer?

Regular Seminar Toby Wiseman (Imperial College London)

at:
13:15 KCL
room S2.49
abstract:

We consider the energy of a (2+1)-d relativistic QFT on a deformation of flat space in either the quantum or thermal vacuum state. Looking at both free scalars and fermions, with and without mass (and in the scalar case including a curvature coupling) we surprisingly find that any deformation of flat space is always energetically preferred to flat space itself. This is a UV finite effect, insensitive to any cut- off. We see the same behaviour for any (2+1)-holographic CFT which we compute via the gravity dual. We consider the physical application of this to membranes carrying relativistic degrees of freedom, the vacuum energy of which then induce a tendency for the membrane to crumple. An interesting case is monolayer graphene, which experimentally is observed to ripple, and on large scales can be understood as a membrane carrying free massless Dirac degrees of freedom.

12.12.2018 (Wednesday)

An Etude on 3d N=2 Conformal Manifolds

Regular Seminar Nikolay Bobev ( KU Leuven)

at:
13:15 KCL
room S2.49
abstract:

I will describe the one-dimensional complex conformal manifold that controls the infrared dynamics of a three-dimensional N=2 supersymmetric theory of three chiral superfields with a cubic superpotential. Two special points on this conformal manifold are the XYZ model and three decoupled copies of the critical Wess-Zumino model. The conformal manifold enjoys a discrete duality group and can be thought of as an orbifold of CP^1. I will discuss how to compute the spectrum of low lying operators and their OPE coefficients as a function of the coordinate on the conformal manifold using the epsilon-expansion and the numerical conformal bootstrap.

04.12.2018 (Tuesday)

Coulomb branches and mock modular forms

Informal Seminar Giorgios Korpas (Trinity College, Dublin)

at:
10:15 KCL
room K6.63
abstract:

“We revisit Donaldson-Witten theory, that is the N=2 topologically twisted super Yang-Mills theory with gauge group SU(2) or SO(3) on compact 4-manifolds. We study the effective action in the Coulomb branch of the theory and by considering a specific Q-exact deformation to the theory we find interesting connections to mock modular forms. A specific operator of this theory computes the famous Donaldson invariants and our analysis makes their computation more accessible than previously. We also extend these ideas to the case of ramified Donaldson-Witten theory, that is the theory in the presence of embedded surfaces. Our results make calculations of correlation functions of Coulomb branch operators more trackable and we hope that they can help in the search of new 4-manifold invariants.”

28.11.2018 (Wednesday)

The Cross Anomalous dimension in N=4 super Yang--Mills

Regular Seminar Hagen Munkler (ETH Zurich)

at:
13:15 KCL
room K3.11
abstract:

The cross or soft anomalous dimension matrix describes the renormalization of Wilson loops with a self-intersection and is an important object in the study of infrared divergences of scattering amplitudes. I will discuss it for the case of the Maldacena--Wilson loop in N=4 supersymmetric Yang--Mills theory, considering both the strong-coupling description in terms of minimal surfaces in AdS5 as well as the weak-coupling side up to the two-loop level. In either case, the coefficients of the cross anomalous dimension matrix can be expressed in terms of the cusp anomalous dimension. The strong-coupling description displays a Gross--Ooguri phase transition and I will argue that the cross anomalous dimension is an interesting object to study in an integrability-based approach.

21.11.2018 (Wednesday)

Wilson Surface Central Charge

Regular Seminar Andy O'Bannon (University of Southampton)

at:
13:15 KCL
room S2.49
abstract:

M-theory is currently our best candidate for a theory of everything, but remains mysterious. We know M-theory has M2- and M5-branes. The low-energy theory on a stack of coincident M2-branes is well-understood: it is maximally supersymmetric Chern-Simons-matter theory. However, the low-energy theory on a stack of coincident M5-branes remains poorly-understood: it is a maximally supersymmetric theory of self-dual strings with zero tension. In this talk I will discuss one type of probe of the M5-brane theory, namely self-dual strings with infinite tension. These play a role analogous to Wilson lines in gauge theories, but are two-dimensional surfaces rather than lines, and hence are called Wilson surfaces. I will describe holographic calculations of entanglement entropy associated with these infinite-tension self-dual strings, from which we extract a key parameter characterizing them, their central charge. This provides a count of the number of massless degrees of freedom living on them, and thus may shed light on some of the fundamental degrees of freedom of M-theory.

14.11.2018 (Wednesday)

Logarithmic terms in entanglement entropy: black holes, anomalies and boundaries

Regular Seminar Sergey Solodukhin (University of Tours)

at:
13:15 KCL
room S2.49
abstract:

In my talk I will give a review on the logarithmic terms that appear in the entanglement entropy, their relation to conformal anomaly and the geometry of the entangling surfaces. I will discuss how the presence of boundaries may effect these terms.

14.11.2018 (Wednesday)

A nAttractor mechanism for AdS(2) quantum gravity.

Regular Seminar Finn Larsen (University of Michigan)

at:
14:30 KCL
room S2.49
abstract:

We study the nearly AdS(2) geometry of nearly extremal black holes in N = 2 supergravity in four dimensions. In the strictly extreme limit the attractor mechanism for asymptotically flat black holes states that the horizon geometries of these black holes are independent of scalar moduli. We determine the dependence of the near extreme geometry on asymptotic moduli and express the result in simple formulae that generalize the extremal attractor mechanism to nearly extreme black holes. This is a nAttractor mechanism. We discuss the dependence of the near horizon theory on the scales introduced by generic attractor flows.

07.11.2018 (Wednesday)

AdS_2 holography - Mind the Cap!

Triangular Seminar Iosif Bena (IPHT)

at:
15:00 KCL
room S-1.04
abstract:

Black holes appear to lead to information loss, thus violating one of the fundamental tenets of Quantum Mechanics. Recent Information-Theory-based arguments imply that information loss can only be avoided if at the scale of the black hole horizon there exists a structure (commonly called fuzzball or firewall) that allows information to escape. I will discuss the highly-unusual properties that this structure must have and how these properties emerge in the realization of this structure in String Theory via branes, fluxes and topology. I will then describe the implication of this structure for AdS_2 holography.

07.11.2018 (Wednesday)

dS vacua and the swampland

Triangular Seminar Timm Wrase (TUWIEN)

at:
16:00 KCL
room S-1.04
abstract:

After briefly reviewing dark energy, dS vacua and the standard model of cosmology, I will discuss recent conjectures that say that metastable dS vacua cannot arise in string theory. These conjectures lead to interesting observational predictions and are currently being tested experimentally. On the theoretical side I will discuss the support for these conjectures as well as the status of explicit counter examples like the KKLT and LVS scenario.

07.11.2018 (Wednesday)

After-talk reception

Regular Seminar Every One (KCL)

at:
17:00 KCL
room Staff Common Room Kings Building
abstract:

After-talk reception at Staff Common Room King's Building

31.10.2018 (Wednesday)

Effective actions for near extremal black holes and gauge fields in AdS2

Regular Seminar Ioannis Papadimitriou (KIAS)

at:
13:15 KCL
room S2.49
abstract:

I will discuss consistent reductions of pure AdS gravity in 3D and 5D to 2D and use them to derive effective actions for the near conformal quantum mechanics dual to the near extremal BTZ and Kerr-AdS5 black holes, respectively. The role of AdS2 gauge fields and their boundary conditions will be discussed in detail.

24.10.2018 (Wednesday)

Conformal field theory in momentum space

Regular Seminar Kostas Skenderis (University of Southampton)

at:
13:15 KCL
room S2.49
abstract:

I will give an overview of the topic and I will discuss the non-perturbative derivation of 3-point functions of scalar operators, symmetry current and energy momentum tensor in momentum space, including renormalization and anomalies. Based on 1805.12100, 1711.09105, 1510.08442, 1304.7760.

17.10.2018 (Wednesday)

Twisting and localization in supergravity: equivariant cohomology of BPS black holes

Regular Seminar Imtak Jeon (KCL)

at:
13:15 KCL
room S2.49
abstract:

We develop the formalism of supersymmetric localization in supergravity using the deformed BRST algebra defined in the presence of a supersymmetric background as recently formulated in arxiv:1806.03690. The gravitational functional integral localizes onto the cohomology of a global supercharge Q, obeying Q2=H, where H is a global symmetry of the background. Our construction naturally produces a twisted version of supergravity whenever supersymmetry can be realized off-shell. We present the details of the twisted graviton multiplet and ghost fields for the superconformal formulation of four-dimensional N=2 supergravity. As an application of our formalism, we systematize the computation of the exact quantum entropy of supersymmetric black holes. In particular, we compute the one-loop determinant of the QV deformation operator for the off-shell fluctuations of the Weyl multiplet around the AdS2×S2 saddle. This result, which is consistent with the corresponding large-charge on-shell analysis, is needed to complete the first-principles computation of the quantum entropy.

10.10.2018 (Wednesday)

Connecting the weak gravity conjecture to the weak cosmic censorship

Regular Seminar Jorge Santos (University of Cambridge)

at:
13:15 KCL
room S2.49
abstract:

I will describe some counterexamples to (weak) cosmic censorship in anti-de Sitter spacetime that have been found recently. These are solutions in which the curvature grows without bound in a region of spacetime visible to infinity. I will also discuss a surprising connection between some of these counterexamples and an apparently unrelated conjecture called the weak gravity conjecture.

26.09.2018 (Wednesday)

Gravitational free energy in topological AdS/CFT

Regular Seminar Paul Richmond (King's College London)

at:
13:15 KCL
room S2.49
abstract:

TBA

16.05.2018 (Wednesday)

Exotic Rational CFT and the Modular Bootstrap

Regular Seminar Sunil Mukhi (IISER Pune)

at:
13:15 KCL
room K4.31
abstract:

I will summarise old and recent developments on the classification and solution of Rational Conformal Field Theories in 2 dimensions using the method of Modular Differential Equations. Novel and exotic theories are found with small numbers of characters and simple fusion rules, one of these being the Baby Monster CFT. Correlation functions for many of these theories can be computed using crossing-symmetric differential equations.

28.03.2018 (Wednesday)

Topological AdS/CFT

Regular Seminar James Sparks (Oxford)

at:
13:15 KCL
room K4.31
abstract:

TBA

27.03.2018 (Tuesday)

Complete factorization in minimal N=4 Chern-Simons-matter theory

Journal Club Shuichi Yokoyama (Kyoto University)

at:
14:00 KCL
room S4.36
abstract:

I and my collaborator, T.Nosaka, revisited minimal N = 4 Chern-Simons theories from its exact S3 partition function, which reduces to finite-dimensional matrix models by supersymmetric localization. We found some new aspects of this interesting model and main results are listed below. [1] The integration in a matrix model of S3 partition function may be performed completely by using the technique called the Fermi-gas analysis. [2] The resulting partition function completely factorized into that of pure CS theory for two gauge groups and an analogous contribution for the bifundamental hypermultiplet. We call this complete factorization. [3] We presented the all order ’t Hooft expansion of the free energy and discussed the connection to the higher-spin theory in the dual gravity side. [4] The level/rank (or Seiberg-like) duality, which is expected from the Hanany-Witten transition in the type IIB brane realization, was confirmed from the factorized partition function up to an overall factor, which may be a signal of existence of some decoupled sector. If time permits, I may touch our ongoing analysis of such decoupled sector more precisely by using a superconformal index.