The discovery of integrability in planar N=4 SYM theory led to considerable advances in the computation of its planar anomalous dimension spectrum. Less is known at the non-planar level where the theory is assumed to be non-integrable. I will show how statistical properties of numerical anomalous dimension spectra can give insight into the symmetries of the underlying model and that the N=4 SYM non-planar spectrum and its beta-deformed version are well described by random matrix theory, indicating their quantum-chaotic nature. Doing so I will also discuss on-going work on using on-shell methods to obtain the dilatation operator for deformed versions of N=4 SYM theory. [for zoom link please contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

Recently there has been great success in describing the inspiral phase of compact binary coalescence in General Relativity (GR) using scattering amplitudes. These efforts aim to improve the precision of gravitational wave (GW) templates used by detectors to identify GW events and test GR. The majority of this work has focused on describing a pair of objects that do not tidally deform. However real objects do tidally deform, and future GW detectors will be increasingly sensitive to such deformations. It has been shown that scattering amplitudes are applicable to the description of tidal effects as well. In this talk we discuss the application of the Hilbert series to the characterization of an entire class of tidal effects: those involving two powers of the Weyl tensor and objects with spin 0 and 1/2. The Hilbert series guides us in the construction of actions describing these effects, which we then use to calculate the leading-PM tidal scattering amplitude. With the amplitude in hand, we compute several classical quantities and compare to the literature where possible. [for zooom link please contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

The study of possible constraints on RG flows is an important question in our understanding of quantum field theory. In this talk I will discuss a constraint which arises by considering the spectrum of BPS excitations (an H-theorem). Examples are found in the context of four-dimensional supersymmetric quantum field theories with enough supersymmetry that the BPS spectrum is explicitly computable. Among others, we will discuss applications in the context of Maruyoshi-Song flows. [for zoom link please contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

[for zoom link please email s.nagyATqmul.ac.uk] After a brief review of the cutoff-surface formulation of fluid-gravity duality, we explore the ``square root'' of the fluid-dual metrics via the classical-double copy, highlighting the constant vorticity flows and potential flows which have algebraically special Weyl double copy fields. We then present progress towards building the same map, from fluid solutions to gravitational solutions to Maxwell solutions, for generic fluids in 2+1 dimensions. This talk is based on JHEP 08 (2020) 147 published with ASU students Nikhil Monga and Tucker Manton, and forthcoming work.

Abstract: We are faced with an explosion of data in many areas of physics, but very so often, it is not the size but the complexity of the data that makes extracting physics from big datasets challenging. As I will discuss in this talk, data has shape and the shape of data encodes the underlying physics. Persistent homology is a tool in computational topology developed for quantifying the shape of data. I will discuss three applications of topological data analysis: 1) identifying structure of the string landscape, 2) constraining cosmological parameters from CMB measurements and large scale structures data, and 3) detecting and classifying phases of matter. Persistent homology condenses these datasets into their most relevant (and interpretable) features, so that simple statistical pipelines are sufficient in these contexts. This suggests that TDA can be used in conjunction with machine learning algorithms and improves their architecture. [for zoom link please contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

[There will be a pre-seminar for students starting at 13:30. For zoom link please email s.nagyATqmul.ac.uk] The relation between the physics of the bulk and that of a boundary plays an important role in quantum field theories, quantum gravity and condensed matter physics. In this talk, I will review a manifestation of this relation that can be summarized as a short statement: "the bulk is the center of a boundary". I will explain the meaning of "center" and provide a formal proof of this statement (arXiv:1702.00673). By including higher codimensional domain walls between boundaries, the boundary-bulk relation can be formulated mathematically as a higher functor. In lower dimensional cases, it becomes precise mathematical theorems. In the end, I will discuss the significances of this relation in the study of topological orders and topological phase transitions.

[for zoom link, please email s.nagyATqmul.ac.uk] We formulate conjectures relating the geometry of conformal manifolds to the spectrum of local operators in conformal field theories in d>2 spacetime dimensions. We focus on conformal manifolds with limiting points at infinite distance with respect to the Zamolodchikov metric. Our central conjecture is that all theories at infinite distance possess an emergent higher-spin symmetry, generated by an infinite tower of currents whose anomalous dimensions vanish exponentially in the distance. Our conjectures are related to the Distance Conjecture in the swampland program. We discuss the supporting evidence, their holographic interpretation, and implications for superconformal field theories.

[For zoom link please email s.nagyATqmul.ac.uk There will be a pre-seminar for students at 13:30] I will discuss the geometric interpretation of the twisted index of 3d supersymmetric gauge theories on a closed Riemann surface. I will show that the twisted index reproduces the virtual Euler characteristic of the moduli space of solutions to vortex equations on the Riemann surface. I will also discuss 3d N = 4 mirror symmetry in this context, which implies non-trivial relations between enumerative invariants associated to the moduli space of vortices. Finally, I will comment on level structures and a wall-crossing formula of the twisted indices derived from the gauge theory point of view.

We study operators with a bare dimension that grows as N^2 in the large N limit. These operators are labeled by a Young diagram with p long rows, as well as a graph, with p nodes. The dilatation operator describing the mixing of these operators defines a Hamiltonian for excitations hopping on this graph. The scrambling and equilibration of the resulting dynamics is studied. [For zoom link please contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

[there will be a 30min pre-seminar for students. For zoom link, please contact s.nagyATqmul.ac.uk] Abstract: Recent work has broadened the scope of scattering amplitudes to include large, classical objects such as the Kerr black hole. This new perspective illuminates surprising aspects of classical gravity, such as the Newman-Janis shift relating Kerr to Schwarzschild. I will describe the connection between amplitudes and classical physics, focussing on the case of Kerr.

QCD instantons are arguably the best motivated yet unobserved nonperturbative effects predicted by the Standard Model. A discovery and detailed study of instanton-generated processes at colliders would provide a new window into the phenomenological exploration of QCD and a vastly improved fundamental understanding of its non-perturbative dynamics. We present for the first time a full calculation of QCD instanton-induced processes in proton-proton collisions accounting for quantum corrections due to both initial and final state gluon interactions. Although QCD instanton processes are predicted to be produced with a large scattering cross-section at small centre-of-mass partonic energies, discovering them at hadron colliders is a challenging task that requires dedicated search strategies. [Based on https://arxiv.org/abs/2010.02287 and https://arxiv.org/abs/1911.09726.] [for zoom link contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

[For zoom link please contact s.nagyATqmul.ac.uk. There will be a pre-seminar for students at 13:30] The energy-energy correlation (EEC) measures the angular distribution of the energy that flows through two calorimeters separated by some relative angle in the final state created by a source. We present a new approach to computing this observable that exploits the relation between the energy correlations and four-point correlation functions of conserved currents. In the limit of small and large angles, when EEC describes the correlation between particles belonging, respectively, to the same jet and to two almost back-to-back jets, we obtain a concise representation of the EEC in terms of the conformal data of twist-two operators and verify it by comparing with the results of explicit calculation at next-to-next-to-leading order in maximally supersymmetric Yang-Mills theory. As a byproduct of our analysis, we predict the maximal weight part of the analogous QCD expression.

We propose an operator product expansion for planar form factors of local operators in N = 4 SYM theory. This expansion is based on the dual conformal symmetry of these objects or, equivalently, the conformal symmetry of their dual description in terms of periodic Wilson loops. A form factor is decomposed into a sequence of known pentagon transitions and a new universal object that we call the “form factor transition”. This transition is subject to a set of non-trivial bootstrap constraints, which allows us to bootstrap it at any value of the coupling. We evaluate the form factor transition for MHV form factors of the chiral half of the stress tensor supermultiplet at leading order in perturbation theory and use it to produce OPE predictions at any loop order. We match the one-loop and two-loop predictions with data available in the literature. [for zoom link contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk]

[For zoom details please email s.nagyATqmul.ac.uk There will be a pre-seminar for students at 13:30] Knot theory plays an important role in physics, mathematics and biology. Characterizing knots is, however, a difficult task. There are different ways to represent a knot (e.g. via braids, Gauss codes, Dowker-Thistlethwaite notation), and many knot invariants exist (e.g. the Alexander polynomial, Jones polynomial, determinant, slice genus). However, it is not known whether these can be used to identify a trivial knot, the so-called unknot. We use different machine learning techniques to tackle this question. First, we use a very recent neural network architecture developed for natural language processing, called the reformer, to decide whether a given knot is the unknot. We also apply Reinforcement Learning to solve the harder problem of finding a set of Reidemeister/Markov moves that explicitly simplify a given knot as much as possible. If the algorithm finds a sequence of moves that removes all crossings of a knot in a given representation, then this knot is provably the unknot.

I will explain that the notion of quantum entanglement is not defined for gravitationally anomalous two-dimensional theories, because they do not admit a local tensor factorization of the Hilbert space into local Hilbert spaces. Qualitatively, the modular flow cannot act consistently and unitarily in a finite region, if there are different numbers of states with a given energy traveling in the two opposite directions. I will make this precise by decomposing it into two observations: First, a two-dimensional conformal field theory admits a consistent quantization on a space with boundary only if it is not anomalous. Second, a local tensor factorization always leads to a definition of consistent, unitary, energy-preserving boundary condition. As a corollary I will establish a generalization of the Nielsen-Ninomiya theorem to all two-dimensional unitary local quantum field theories: No continuum quantum field theory in two dimensions can admit a lattice regulator unless its gravitational anomaly vanishes. I will advocate that these points be used to reinterpret the gravitational anomaly quantum-information-theoretically, as a fundamental obstruction to the localization of quantum information. [Zoom link: please ask your local triangle organizer]

I will summarize recent developments on the information paradox involving "islands" and replica wormholes, and discuss the extent to which these ideas can be applied to cosmology. [Zoom link: please ask your local triangle organizer]

[Please inqure jung-wook(dot)kim(at)qmul(dot)ac(dot)uk for the zoom link] Taking advantage of mathematical similarities between grammar models and quantum theory, we present a canonical way of instantiating grammatical sentences as quantum circuits. In the context of quantum machine learning, we define toy natural language processing tasks and implement them on readily accessible quantum processors, such as those provided by IBMQ.

[there will be a 15 min pre-seminar for students. For zoom link, please email s.nagyATqmul.ac.uk] Abstract: Recent progress in understanding de Sitter spacetime in supergravity and string theory has led to the development of a 4D supergravity with spontaneously broken supersymmetry allowing for de Sitter vacua, also called de Sitter supergravity. One approach makes use of constrained (nilpotent) superfields, while an alternative one couples supergravity to a locally supersymmetric generalization of the Volkov-Akulov goldstino action. These two approaches have been shown to give rise to the same 4D action. A novel approach to de Sitter vacua in supergravity involves the generalisation of unimodular gravity to supergravity using a super-Stückelberg mechanism. We make a connection between this new approach and the previous two. We show that upon appropriate field redefinitions, the 4D actions match up to the cubic order in the fields. This points at the possible existence of a more general framework to obtain de Sitter spacetimes from high-energy theories.

Abstract: In two dimensional topologically ordered matter, processes depend on gross topology rather than detailed geometry. Thinking in 2+1 dimensions, particle world lines can be interpreted as knots or links, and the amplitude for certain processes becomes a topological invariant of that link. While sounding rather exotic, we believe that such phases of matter not only exist, but have actually been observed in quantum Hall experiments, and could provide a route to building a quantum computer. Possibilities have also been proposed for creating similar physics in systems ranging from superfluid helium to topological superconductors to semiconductor-superconductor junctions to quantum wires to spin systems to graphene to cold atoms. Please contact jung-wook(dot)kim(at)qmul(dot)ac(dot)uk for the zoom link.

For zoom link please email s.nagyATqmul.ac.uk There will be a pre-seminar for students at 13:30. Abstract: I will discuss 2 recent results arising out of the recent resurgence in concrete tests / predictions of AdS/CFT over the last few years. The first is the precise identification of the CFT operators dual to single particle supergravity states (based on 2007.095395) and the second is a forthcoming work explicitly relating four-point correlators to a string effective action on AdSxS.