We are located at the 6th floor of the G.O. Jones Building on the Mile End Campus, midway between Stepney Green and Mile End Tube stations, approximately 1520 minutes from central London on the Central or District lines. If exiting Stepney Green tube station, turn left and walk along the Mile End Road for approximately 300 metres. The G.O. Jones (Physics) building is to the right of the main college building, which is fronted by a clocktower and lawn. If exiting Mile End tube station, turn left and walk approximately 300 metres until you are opposite the main college building. A more detailed description can be found here.
Found at least 20 result(s)
Regular Seminar Ingo Runkel (Hamburg U.)
at: 14:00 room 610  abstract: I would like to discuss a class of threedimensional topological field theories called ReshetikhinTuraev theories. Examples are ChernSimons theories with compact gauge group. There are no pointlike observables in these theories, and one typically considers lineobservables, called Wilson lines. However, one can also discuss observables associated to surfaces. We will see how to describe such observables in ReshetikhinTuraev TQFTs and look at some applications. 
Regular Seminar Fei Teng (Uppsala University)
at: 14:00 room G O Jones 610  abstract: In this talk, I will connect, via treelevel double copy, any massless string amplitudes with QFT amplitudes given by CachazoHeYuan (CHY) formula. This can be derived by a detailed study of integrationbypart (IBP) reduction of string integrands. As an application, we consider general multitrace integrands of heterotic string amplitudes. The new technology generates a recursive expansion of the heterotic string amplitudes in terms of those with fewer gravitons and traces, where the kinematic coefficients are building blocks for BCJ numerators of the (DF)^2+YM+phi^3 theory. Finally, we give a generic CHY integrand for multitrace (DF)^2+YM+phi^3 amplitudes, which reproduce the corresponding heterotic string amplitudes after double copy with a singlevalued Ztheory. 
Journal Club Gim Seng Ng (Trinity College Dublin)
at: 15:00 room G O Jones 610  abstract: We study the leading and nexttoleading eikonal phase in the context of AdS/CFT. In the bulk side, we compute the phase shift of a highly energetic particle traveling in the background of an asymptotically AdS black hole. In the dual CFT, the phase shift is related to a four point function in the Regge limit. The black hole mass is translated to the ratio between the conformal dimension of a heavy operator and the central charge. This ratio serves as a useful expansion parameter; its power measures the number of stress tensors appearing in the intermediate channel. The leading eikonal phase shift in 4d holographic CFTs can be computed using conformal Regge theory while the computation of the nexttoleading order eikonal phase shift relies on a new universal formula for the lowesttwist OPE of doubletrace stresstensors with two scalar operators. These OPE coefficients are consistent with the secondorder phase shift as well as anomalous dimensions obtained in AdS black holes in the lightcone limit. In relations to the idea of “eikonalization” of the stresstensor sector in holographic CFTs, we comment on hints of a structure similar to the vacuum Virasoro block in 2d CFT. 
Regular Seminar Saso Grozdanov (MIT)
at: 14:00 room G O Jones 610  abstract: Hydrodynamic excitations corresponding to sound and diffusive modes in fluids are characterised by gapless dispersion relations. In the hydrodynamic gradient expansion, their frequencies are represented by infinite power series in spatial momenta. I will discuss how the introduction of a new concept of the hydrodynamic complex spectral curve in the space of complexified frequency and spatial momentum—the concept otherwise known from algebraic geometrycan be used to prove general properties about hydrodynamics, including its finite radius of convergence. When the infinite series are resummed, they exhibit a fascinating, recentlydiscovered phenomenon of poleskipping, which enables us to analyse the underlying, microscopic quantum manybody chaos in the system. Throughout my talk, I will use gaugegravity duality as a tool to explicitly show these phenomena in holographic systems and discuss what their implications are for the dual gravity theory. 
Exceptional Seminar Andrey Gromov (Brown U.)
at: 15:00 room G.O. Jones 610  abstract: Fractional quantum Hall (FQH) states are topologically ordered. Additionally, FQH states support a collective neutral excitation known as the GirvinMacDonaldPlatzman (GMP) mode. Certain features of this mode are independent of the microscopic details. The objective of the talk is to construct an effective theory includes both topological properties and the massive GMP mode. The theory reproduces the universal properties of chiral lowest Landau level (LLL) FQH states which lie beyond the TQFT data, such as the projected static structure factor and the GMP algebra of areapreserving diffeomorphisms. The dynamics of the mode is described by a fluctuating rank2 symmetric, positivedefinite tensor, which leads to a natural geometric (or gravitational) interpretation of the GMP mode. 
Regular Seminar Michele Levi (IPhT Saclay)
at: 14:00 room G O Jones 610  abstract: This talk presents the progress made in my research via the introduction of effective field theories (EFTs) into postNewtonian (PN) gravity. These have been put forward in the context of gravitational waves (GWs) from the compact binary inspiral. The setup and the strategy of a multistage EFT framework, which is deployed for the PN binary inspiral problem, is outlined. I then present in more detail the study of two effective theories at the intermediate scales of the problem. First, the EFT for a single rotating compact object is considered, from which I proceed to the EFT of a compact binary system, viewed as a composite particle with internal binding interactions. I conclude with the prospects of building on the field, and using further modern field theory insights and tools, to address the study of GWs, as well as to expand our fundamental understanding of QFTs and gravity theories at all scales. 
Regular Seminar Franz Ciceri (AEI Potsdam)
at: 15:00 room G O Jones 610  abstract: Supersymmetric extensions of conformal gravity have been known for a long time. In four dimensions, N=4 conformal supergravity is the maximally supersymmetric theory of this type. Although its field representation and the nonlinear transformations rules were derived more than 30 years ago, no invariant action had been constructed so far. We present the most general class of actions which turns out to be characterised by a holomorphic function. This deviates from the nonmaximally supersymmetric cases where the action is unique. Meanwhile, elaborate loop computations have indicated that N=4 Poincare supergravity diverges at four loops, and the divergence is believed to be related to the presence of a potential oneloop anomaly in the duality symmetry of the theory. We argue that one of the constructed conformal actions, after gauge fixing the conformal symmetries and carefully eliminating auxiliary fields, can be used as a finite supersymmetric counterterm that cancels the anomalous contribution of the oneloop graphs in the Poincare theory. 
Regular Seminar Jaco van Zyl (Witwatersrand U.)
at: 14:00 room G O Jones 610  abstract: The 1/2 BPS and regular LLM geometries are formed from the backreaction of a large number of Dbranes on AdS_5 x S^5. The dual N=4 SYM operator to this configuration, and excitations thereof, thus lie outside of the planar limit of the theory. Explicitly the operators dual to these geometries are Schur polynomials labelled by a Young diagram with O(N^2) boxes and excitations of this configuration are restricted Schur polynomials obtained by adding boxes (and restriction labels) to this diagram. A special class of these geometries are labelled by Young diagrams with O(1) well separated corners. In the large N limit excitations localised at any one of these corners only mix with each other which is a major simplification. A recent proposal has argued that the large N dynamics of these operators is isomorphic to that of planar N=4 SYM and thus represents an integrable subsector of N=4 SYM. In this talk this proposal is reviewed and aspects of the weak and strong coupling evidence presented. 
Regular Seminar Rohini Godbole (Indian Institute of Science)
at: 15:00 room G O Jones 610  abstract: After a summary of current status of experimental results in particle physics, including the presentation of what I call the LHC paradox, I will discuss briefly how colliders were indispensible in arriving at this point of the journey. After this I would discuss what the next steps are: as to where do we go from here in the story of collider physics. If time is left, I will discuss some of the issues that the future colliders can address , by taking examples from the known unknowns, viz. in the framework of particular BSM models and also the unknown unknowns viz the model independent approach. 
Regular Seminar Simone Giacomelli (Oxford)
at: 14:00 room G O Jones 610  abstract: In this seminar I will discuss a recentlyfound class of RG flows in four dimensions exhibiting enhancement of supersymmetry in the infrared, which provides a lagrangian description of several stronglycoupled N=2 SCFTs. The procedure involves starting from a N=2 SCFT, coupling a chiral multiplet in the adjoint representation of the global symmetry to the moment map of the SCFT and turning on a nilpotent expectation value for this chiral. We show that, combining considerations based on 't Hooft anomaly matching and basic results about the N=2 superconformal algebra, it is possible to understand in detail the mechanism underlying this phenomenon and formulate a simple criterion for supersymmetry enhancement. 
Regular Seminar Anatoly Konechny (HeriotWatt University)
at: 14:00 room G.O. Jones 610  abstract: Renormalisation group (RG) interfaces were introduced by I. Brunner and D. Roggenkamp in 2007. To construct such an interface consider perturbing a UV fixed point, described by a conformal field theory (CFT), by a relevant operator on a half space. Renormalising and letting the resulting QFT flow along the RG flow we obtain a conformal interface between the UV and IR fixed point CFTs. Although enjoying a full conformal symmetry this interface carries information about the RG flow it originated from. In this talk I will consider a rather special case of the RG interface between two boundary conditions of a 2D CFT which is obtained from a boundary RG flow interpolating between two conformal boundary conditions. This interface is zerodimensional and is thus described by a local boundarycondition changing operator. I investigate its properties in concrete models and formulate a number of general conjectures that can help charting phase diagrams of boundary RG flows. 
Regular Seminar Matthew Roberts (Imperial)
at: 14:00 room G O Jones 610  abstract: We construct new supersymmetric solutions of 11D supergravity, preserving 1/4 of the supersymmetry, that are dual to the ABJM ChernSimonsmatter theory deformed by mass terms which depend on one spatial direction. The BPS equations boil down to solving the Helmholtz equation on the complex plane giving rise to rich classes of new solutions. In particular, the construction gives rise to infinite classes of new supersymmetric “boomerang” RG flows, as well as generalising other previously known solutions. 
Regular Seminar David Berenstein (UC Santa Barbara)
at: 14:00 room G O Jones 610  abstract: I will describe simple models of holography that can display some of the thermodynamics associated to small black holes. These phenomena include negative specific heat and localization on additional dimensions of the geometry. I will also explain how the dynamics of these states should naturally be thought of as partial deconfinement on a submatrix set of degrees of freedom of the model. 
Regular Seminar Massimo Bianchi (Roma Tor Vergata)
at: 14:00 room G O Jones 610  abstract: Ultraplanckian collisions represent a fertile arena where to test quantum theories of gravity such as string theory. Glimpses of black hole formation and evaporation can be taken. For suitably defined infraredsafe observables, we show that the `classicalization' approach to highmultiplicity processes agrees with the ACV approach based on the resummation of ladder diagrams. Since a significant fraction of energy is lost in gravitational bremsstrahlung, we rederived the zerofrequency limit (ZFL) of the GW flux using soft graviton theorems at leading order and compute the corrections at sub and subsubleading order. For massless twoparticle elastic collisions the former is shown to vanish, while the latter takes an explicit expression which is checked against a simple treelevel process.However, if the treelevel form of the soft theorems is used at subsubleading order even when the elastic amplitude needs resummation, an unphysical IR singularity occurs due to the infinite Coulomb phase. We briefly discuss a recent proposal as how to deal with these divergences and find agreement with the eikonal approach. 
Exceptional Seminar Philip Argyres (University of Cincinnati)
at: 11:00 room G.O. Jones 610  abstract:

Regular Seminar Mahdi Godazgar (QMUL)
at: 14:00 room G O Jones 610  abstract: I will give an overview of my recent research on the definition of asymptotic charges in asymptotically flat spacetimes, including the definition of subleading BMS charges and the relation to the conserved NewmanPenrose charges at null infinity. 
Exceptional Seminar Jeff Harvey (The University of Chicago)
at: 11:30 room 610  abstract: I will discuss some old and new relations between the characters, modular data and braiding and fusing matrices of rational conformal field theories and their associated modular tensor categories. These relations involve concepts from number theory which I will explain in the talk. 
Regular Seminar Marco Meineri (EPFL, Lausanne)
at: 14:00 room G O Jones 610  abstract: We probe a generic two dimensional conformal interface via a collider experiment. We measure the energy and charges which are reflected and transmitted through the interface. We find that the average transmitted energy is independent of the way the state is constructed and determined by the central charge and a single piece of CFT data. We comment on the universality of the result and discuss some examples. 
Regular Seminar Melissa van Beekveld (IMAPP Njimegen)
at: 14:00 room G O Jones 610  abstract: I will show how large logarithms arise in a perturbative calculation and how resummation solves the issue of having these large logarithms. If there is some time left, I want to show some recent progress that we have made on pinning down the origin of the nexttoleading class of logarithms. 