fpuk and the City

2 December 2022


City University



Local Organiser: B. Stefanski

Organising Committee: D. Berman, J. Gauntlett, P. Kumar, N. Lambert, S. Ross, S. Schafer-Nameki, M. Taylor and D. Tong





December 2nd



















Gong Show


Lunch and posters




Carrillo Gonzalez










Wine and cheese



Registration for talks and posters has closed. You are still welcome to attend but please let us know by email





The talks will take place in room BG03 in the University Building, with the poster session and lunch in C302 in Tait building.


The buildings are connected internally and can both be accessed through the card less main entrance in Northampton square.

The nearest tube stops are Farringdon and Angel. King’s Cross/St Pancras train station is about 20 a minute walk.




Connor Behan (Oxford):  Coupled Minimal Models Revisited


It is widely believed that two copies of the 3d Ising model, coupled via their energy operators, will flow to the O(2) model in the IR. In two dimensions, one also has the option of coupling higher minimal models together. These offer a number of underexplored possibilities for triggering RG flows that are arbitrarily weakly coupled. I will give an overview of the zoo of fixed points one can obtain. Importantly, some of the tools most helpful for analyzing them did not exist ten years ago. I will focus on multiplet recombination and how it provides strong evidence for the irrationality of these CFTs.


Mariana Carrillo Gonzalez (Imperial): Massive gravitons from the double copy


The double copy is a relation that allows us to write gravitational phenomena as the "square" of the analog Yang-Mills phenomena. This simplifies involved gravitational calculations and gives an insight into hidden symmetries of gravity. Given the possibility of having a massive graviton that can explain the acceleration of the Universe, it is interesting to understand whether this relationship extends to this case. In my talk I will introduce the BCJ double copy and the color-kinematics duality, and I will explain how to start generalizing this to massive gravitons. I will focus on the 3-dimensional case of topologically massive gravity and will give examples of different realizations of the topologically massive double copy. This presentation will be based on 2111.15405 and 2207.04431.


Andrea Ferrari (Durham): Non-invertible symmetries and higher representation theory


There has recently been a lot of excitement surrounding non-invertible global symmetries and their potential applications. An important question is how to systematically construct theories whose non-invertible symmetry categories we can control well. In this talk I will suggest that higher representation theory can help us to answer this question when the symmetries are non-intrinsically non-invertible. In particular, I will explain how the topological defects obtained after gauging finite groups and 2-groups in 3 dimensions form the category of 2-representations of the original 2-group, and how this fact can be applied to some gauge theories with disconnected gauge groups. The same techniques can be extended to more general higher groups and subgroups in higher dimensions.


Sagar Hosseini (Durham): Generalised Symmetries and anomalies from higher dimensions


Recently, there has been much interest in the study of symmetries in physical systems as they characterise topological aspects of quantum field theories. An important realisation is that symmetries, their anomalies and BF theory in a given QFT may be characterised in one higher dimension by a symmetry topological field theory (SymTFT) via inflow mechanics. Such descriptions can naturally emerge whenever we can construct quantum field theories from string theory. In this talk, I will introduce SymTFTs and explain how to construct them from geometry.


Julius Julius (KCL): Bootstrability for 1d defect CFT

I will describe the bootstrability program, which combines integrability techniques in 4d N = 4 SYM and the conformal bootstrap to study beyond-the-spectrum observables in a CFT.

I will start with a quick review of the quantum spectral curve (QSC), a powerful integrability based method to compute the non-perturbative planar spectrum of N = 4 SYM. I will show how it is modified to capture the spectrum of operator insertions on a 1/2-BPS Maldacena-Wilson line in the theory, thus solving the spectral problem of the associated defect CFT.

Then, I will show how the boostrability approach allows us to access previously unreachable quantities such as correlation functions at finite coupling ‚Äî we used this method to compute with good precision a non-supersymmetric structure constant for a wide range of the ‘t Hooft coupling in the defect CFT.

Finally, I will present recent results, where we included further spectral input, in order to derive novel integral constraints for our bootstrap procedure, which allows us to improve the precision of our results by several orders of magnitude.


Avner Karasik (Cambridge): On anomalies and gauging of U(1) non-invertible symmetries in 4d QED.


I will present a way to promote the anomalous axial U(1) in 4d QED to an exact symmetry, with the price of losing its invertibility. I will then discuss some applications of this non-invertible U(1) symmetry. In particular, I will show how to gauge this symmetry and how to study its 't-Hooft anomalies.Based on 2211.05802


Rifath Khan (Cambridge): Cauchy Slice Holography


In the Canonical theory of Quantum Gravity (CQG), states are given by the superposition of geometries on a Cauchy slice, called the Wheeler-DeWitt (WDW) states. On the other hand, the Holographic principle states that quantum gravity in d+1 spacetime dimensions is the same as a quantum field theory in d spacetime dimensions. In this talk, I will briefly review both of these and will explain how to reformulate CQG as a holographic theory by defining a new holographic dictionary that maps any state of the boundary field theory to a bulk WDW state. This dictionary is an isomorphism between the Hilbert space of CQG and holographic CFT. This also reformulates the holographic principle in a way that the dual field theory now lives on Cauchy slices of the bulk, hence applicable to dS and flat spacetimes too. I will then explain why this is a manifestly background independent theory of effective quantum gravity. Time permitting, I will also discuss UV completion of quantum gravity, and holographic cosmology. Based on work with Goncalo Araujo-Regado and Aron C. Wall: arXiv:2204.00591.


Sujay Nair (Oxford): Chiral algebras for twisted class S


The SCFT/VOA correspondence of Beem-Lemos-Liendo-Peelaers-Rastelli-van Rees leads to a particularly rich family of vertex algebras when applied to the theories of class S. A remarkably uniform construction of these, so called, 'chiral algebras of class S' has been put forward by Arakawa in arxiv:1811.01577. This construction takes a simple Lie algebra as an input and applies equally well in the non-simply laced case. However, the non-simply laced construction does not correspond, in any clear way, to known four-dimensional theories.


Physically, the incorporation of non-simply laced symmetry algebras requires the inclusion of outer automorphism twists. I will detail an extension of Arakawa's construction to this twisted setting. The resulting, novel vertex algebras have interesting mathematical properties and can be used to make non-trivial predictions about the low energy limits of these SCFTs. Based on joint work with C. Beem, arXiv:2201.13435


Praxitelis Ntokos (Edinburgh): On the uniqueness of supersymmetric AdS_5 black holes with toric symmetry


In this talk, I will describe recent progress on the classification of supersymmetric AdS_5 black holes to minimal gauged supergravity. For solutions with a torus symmetry, this classification reduces to a problem in toric Kahler geometry which is most conveniently formulated in terms of a symplectic potential. The singular behaviour of the latter at the boundary of the orbit space encodes the horizon and axis structure of any possible BPS black hole spacetime within the toric class. I will also present the first uniqueness theorem(s) for supersymmetric AdS_5 black holes: any supersymmetric and toric solution that is timelike outside a smooth horizon, with a Kahler base metric of Calabi type, must be the BPS limit of the (Chong, Cvetic, Lu, Pope) CCLP black hole solution or its near-horizon geometry, based on arXiv: 2208.00896


Enrico Parisini (Southampton): An embedding formalism for CFTs in general backgrounds and states


Conformal field theories exhibit a high level of control provided by conformal symmetry. However, in many relevant situations conformal symmetry is broken by either the state or the background of the theory, and most of the mathematical control is lost. In this talk I will present a framework generalising the embedding space formalism to compute the observables of CFTs in non-trivial states and on generic backgrounds. In this construction (d+2)-dimensional Minkowski is replaced by a more general Ricci-flat metric, the ambient space by Fefferman and Graham. As an example, I will apply this formalism to the case of 2-point functions in CFTs at finite temperature. I will also comment on the relations with flat holography.


Maxim Trepenier (KCL): Bootstrapping string dynamics in the 6d N = (2, 0) theories


The 6d (2, 0) theories are superconformal field theories believed to describe the low-energy dynamics of N coincident M5-branes. These theories don’t have a known lagrangian description and remain largely mysterious, so it is an interesting question how one might calculate observables there. In this talk I will present two complementary approaches to a case study, the calculation of the 2-point function of stress tensors in the presence of a 1/2 BPS surface defect defined over a plane. First, we use analytical bootstrap techniques at large N to obtain the first nontrivial correction to this correlator, from which we extract the

defect CFT (dCFT) data characterising the 2d dCFT of the 1/2 BPS plane. Along the way we derive a supersymmetric inversion formula and obtain the relevant superconformal blocks. Notably our result features a holomorphic function whose appearance is related to the chiral algebra construction of Beem et al. Second, we use that chiral algebra description to obtain exact results for the BPS sector of the dCFT, valid at any N and for any choice of surface operator. The setup we present here is remarkably simple and the same techniques can be applied to many more nonlagrangian theories.


Gong Show and Posters:


Thomas Bartsch (Durham): Non-invertible symmetries and higher representation theory


Andrea Boido (Oxford): A gravitational block formula for spindle geometries


David Bonomi (City): Analytic bootstrap for defect CFTs


Calvin Chen (IC): Causality and Gravitational EFTs


Arpit Das (Durham): Chiral magnetohydrodynamics, Symmetries and Holography


Mang Hei Gordon Lee (Cambridge): Analytic Structure of Wavefunction Coefficients


Suvajit Majumder (City): Protected states and excited state TBA in AdS3xS3xT4


Rishi Mouland (Cambridge): Black Hole Entropy from Quantum Mechanics


James Pearson (Durham): Non-invertible Symmetries and Higher Representation Theory


Torben Skrzypek (Imperial): Integrability of type 0 and other Orbifolds of AdS5xS5