Michele Schiavina<\/b> (U. Pavia) | Hamiltonian gauge theory with corners. Soft symmetries, memory and superselection from Hamiltonian reduction by stages<\/em><\/strong><\/p>\n A general paradigm in classical mechanics is that a mechanical system with integrable (i.e. Hamiltonian) symmetries can be reduced by fixing a value of the associated conserved quantity. When the symmetry group admits a normal subgroup, reduction can be done in steps, and one gets \u00ab\u00a0intermediate phase spaces\u00a0\u00bb that can be useful for various applications. This procedure is called Hamiltonian reduction by stages, and it extends to gauge field theory, where it becomes subtler due to the symmetries being local. If one takes the symplectic formulation of gauge theory seriously, by viewing the construction of the reduced phase space of the theory as an example of Hamiltonian reduction, a number of interesting observations ensue when the field theory is defined on manifolds with corners, enabling Hamiltonian reduction by stages due to the existence of the (normal) subgroup of gauge transformations that are \u00ab\u00a0trivial at the corner\u00a0\u00bb. By implementing Hamiltonian reduction by stages within the local gauge theory scenario, I will construct the reduced phase space of a large class of gauge theories, and show how a number of topics in high-energy physics, such as the existence of soft\/asymptotic symmetries (and the conservation of associated charges), as well as various \u00ab\u00a0memory effects\u00a0\u00bb can be seen as a straightforward, albeit highly nontrivial, application of Hamiltonian reduction by stages. This talk is based on two joint works with A. Riello: 2207.00568 and 2303.03531.<\/p>\n Sa\u0161o Grozdanov<\/b> (University of Edinburgh and University of Ljubljana) | Spectra, reconstructions and pole-skipping<\/strong><\/em><\/p>\n The poles of two-point functions in momentum space, which can be computed and analysed using holographic methods, reveal various details of the physical properties of spectra in QFTs. In thermal QFTs, the lowest-energy (IR) gapless mode is usually described by the theory of hydrodynamics. Assuming a known dispersion relation of only a single hydrodynamic mode, I will discuss when and how the reconstruction of the complete spectrum of physical excitations is possible in the corresponding correlator. In particular, I will demonstrate our recently developed constructive algorithm based on the theorems of Darboux and Puiseux that allows for a reconstruction of all modes connected by `level-crossings\u2019 in the associated spectral curve, from IR to UV. In the second part of my talk, I will introduce the phenomenon of pole-skipping (formally, a \u201c0\/0\u201d) in such correlators and discuss how its knowledge can itself be sufficient to reconstruct the entire spectrum.<\/p>\n <\/p>\n Gary Shiu<\/b> (University of Wisconsin-Madison & BEL Professor) | Quantum Gravity and the Swampland<\/strong><\/em><\/p>\n String theory seems to offer an enormous number of possibilities for low energy physics. The huge set of solutions is often known as the String Theory Landscape. In recent years, however, it has become clear that not all quantum field theories can be consistently coupled to gravity. Theories that cannot be ultraviolet completed in quantum gravity are said to be in the Swampland. In the first two lectures (May 19), I\u2019ll discuss the motivation behind the Swampland program and present some of the better established Swampland criteria such as the absence of exact global symmetries, the various formulations of the Weak Gravity Conjecture(s) and their physical consequences. The axionic version of the Weak Gravity Conjecture also naturally connects Swampland questions with Euclidean wormholes. In Lectures 3 and 4 (May 24), I will focus on challenges in realizing accelerating universes from string theory. I\u2019ll begin with the Dine-Seiberg problem which emphasizes the tension between moduli stabilization in string theory and control of corrections to the effective field theory. Then, I\u2019ll turn to the de Sitter conjecture which highlights further challenges in finding metastable vacua with positive vacuum energy. I\u2019ll end by presenting some recent findings which elucidate the late-time behaviors of cosmological solutions and explain what these behaviors mean for realizing accelerating universes. Throughout the lectures, I hope to convey how the Swampland program meets other areas of high energy theory, such as holography, scattering amplitudes, bootstrap, black hole physics, and dynamical systems.<\/p>\n <\/p>\n Alfredo Gonz\u00e1lez Lezcano<\/b> (APCTP, Pohang) | Supersymmetric localization on AdS2<\/em><\/strong><\/p>\n Application of the supersymmetric localization method to theories on AdS space has received recent interest yet remains a challenging problem. The main obstacle is that supersymmetric transformations do not map into each other the bosonic and fermionic standard delta-function normalizable basis in terms of which the quantum fluctuations are typically expressed. We overcome this problem by constructing a supersymmetric Hilbert space for scalar and spinor fields on Euclidean global AdS2 by considering the complexified spectrum of the Dirac operator. The new basis remains delta-function normalizable with an appropriate inner product and is compatible with the asymptotic boundary condition demanded by the variational principle. Once we have a supersymmetric Hilbert space, we can safely evaluate the path integral using localization. We then focus on (global) Euclidean AdS2, on which we consider an Abelian N=(2,2) theory and implement localization computation to obtain the exact partition function. To evaluate the 1-loop determinant about the localization saddle, we use index theory and fixed-point formula, where we pay attention to the effect of zero modes and their superpartners. The resulting partition function reveals an overall dependence on the size of the background manifold as a sum of two types of contributions: a local one from local conformal anomaly through the index computation and a global one coming from zero modes. This overall size dependence is confirmed by the perturbative 1-loop evaluation using heat kernel method.<\/p>\n Victor Gorbenko<\/strong> (EPFL) | Quantum Fields in de Sitter in Non-perturbative regimes<\/strong><\/em><\/p>\n I will discuss several interconnected topics in inflationary cosmology: dynamics of light fields in dS and in inflation and taming of IR divergences; conformal-partial-waves decomposition of cosmological correlators, constraints that unitarity imposes on it and a formulation of a bootstrap problem.<\/p>\n <\/p>\n Ronak Soni<\/b> (Cambridge University) |\u00a0Towards Tensor Networks with Non-Commuting Areas<\/strong><\/em><\/p>\n There has been much interest recently in discrete toy models of hoolography called tensor networks. This is based primarily on the fact that entanglement between boundary regions is given by a minimal cut of the network, in a way reminiscent of the Ryu-Takayanagi formula in the case of a static bulk geometry. These models have two related shortcomings: they can’t reproduce the full maximin condition relevant in the general case, and they can’t reproduce the fact that the areas of two intersecting RT surfaces are non-commuting operators in the semi-classical theory. This can be traced back to the fact that the tensor networks don’t satisfy any discretised version of the Hamiltonian constraint of gravity. To remedy this situation, we go back to pure GR in three dimensions, which can be rewritten as a topological Chern-Simons theory. A lattice version of Chern-Simons theory, known as the quantum double model or the Levin-Wen model, naturally satisfies a Hamiltonian constraint and also has an analog of non-commuting areas. We propose that these models can be used as a starting point for building holographic tensor networks.<\/p>\n Marine De Clerck<\/b> (Cambridge University) |\u00a0Integrability and complexity in quantum spin chains<\/strong><\/em><\/p>\n There is a widespread perception that dynamical evolution of integrable systems should be simpler in a quantifiable sense than the evolution of generic systems, though demonstrating this relation between integrability and reduced complexity in practice has remained elusive. The notion of complexity of interest to us will be Nielsen\u2019s complexity applied to the time-evolution operator of quantum systems. I will start by reviewing Nielsen\u2019s complexity, discuss the difficulties associated with this definition and introduce a simplified approach that we first considered in arXiv:2202.13924, which appears to retain non-trivial information about the integrable properties of the dynamical systems. Subsequently, I will present recent results from arXiv:2305.00037, where we studied the correlation between integrability and complexity reduction in detail using quantum spin chains which possess diverse integrable structures.<\/p>\n <\/p>\n Matilda Delgado<\/b> (Madrid, IFT) |\u00a0Probing far away regions of moduli space<\/strong><\/em><\/p>\n I will discuss the difficulties one encounters in attempting to probe (near-) infinite distances in moduli space using local solutions of the EFT. I will first argue that one generically runs into spacetime singularities due to the back-reaction on spacetime of such large field excursions. I will then argue that one can solve this issue by considering large black holes. I will focus on 4d N = 2 BPS black holes and use their attractor mechanism to show how one can extract topological data about the underlying compactification by measuring black hole thermodynamic observables. Furthermore, I will illustrate how the standard distance in moduli space can be related asymptotically to the black hole mass and entropy. I will also compute a measure of the resolution with which BPS black holes of a given mass can distinguish far away points in the moduli space. Based on: 2212.08676, 2203.11240.<\/p>\n I\u00f1aki Garc\u00eda Etxebarria<\/b> (Durham U.) |\u00a0Branes and symmetries for N=3 SCFTs<\/strong><\/em><\/p>\n I will explain how to derive various results about the generalised symmetry structure of N=3 and N=4 S-fold SCFTs using holography. The new results in the N=3 case include the spectrum of 1-form symmetries, their ‘t Hooft anomalies, and the existence of non-invertible symmetries for appropriate choices of global form.<\/p>\n <\/p>\n Mart\u00edn Sasieta<\/b> (Brandeis University) |\u00a0Microscopic origin of the entropy of black holes in general relativity<\/strong><\/em><\/p>\n In many situations, the local description of the interior of the black hole is in tension with its universal entropy, given by the Bekenstein-Hawking formula. In this talk, I will start by constructing an infinite family of semiclassical microstates with distinct geometric interiors in the gravitational effective field theory, which naively overcount the entropy of the black hole. I will then show that the gravitational path integral is able to detect non-vanishing overlaps between these states via exponentially suppressed, yet universal, wormhole contributions. I will finally show two ways to use this information to conclude that the Hilbert space spanned by these states is e^S dimensional, where S is the Bekenstein-Hawking entropy of the black hole. I will end with some open questions and future directions.<\/p>\n Christoph Uhlemann<\/b> (University of Oxford) |\u00a0Double holography and Page curves in Type IIB<\/strong><\/em><\/p>\n Randall-Sundrum braneworld models provide a fruitful setting to study gravitational systems coupled to a QFT bath through the concept of double holography, and they are key ingredients in recent studies of the black hole information paradox. However, these bottom-up models are qualitative and their holographic interpretation plagued by causality problems. In this talk we discuss top-down models realizing 4d black holes coupled to a QFT bath in Type IIB string theory and obtain Page curves consistent with unitarity. We make the concept of double holography precise and resolve the causality problems found in the bottom-up models, leading to a refinement of their interpretation.<\/p>\n <\/p>\n Piotr Tourkine<\/b> (Annecy, LAPTh) |\u00a0Scattering amplitudes from dispersive iterations of unitarity<\/strong><\/em><\/p>\n In 1968, D. Atkinson proved in a series of papers the existence of functions satisfying all known constraints of the S-matrix bootstrap for the 2-to-2 S-matrix of scalar, gapped theories, following an approach suggested by Mandelstam. To date, this is the only result of this sort, while a contrario no current technology allows to generate, even numerically, fully UV-complete S-matrices in d>2. Beyond the mathematical results themselves, the proof, based on establishing the existence of a fixed point of a certain map, also suggests a procedure to be implemented numerically and which would produce fully consistent S-matrix functions via iterating dispersion relations, and using as an input a quantity related to the inelasticity of a given scattering process. In this talk, I will present the results of a recent paper in collaboration with A. Zhiboedov, about the first implementation this scheme. I will first review basic concepts of the S-matrix program, and state our working assumptions. I will then present our numerical non-perturbative S-matrices, and discuss some of their properties. They correspond to scalar, massive phi^4-like S-matrices in 3 and 4 dimensions, and have interesting and non-trivial high energy and near-threshold behaviour. They also allow to make contact with the running of the coupling constant. I will also compare to other approaches to the S-matrix bootstrap in the literature.<\/p>\n Stefano Cremonesi<\/b> (Durham U.) |\u00a0Toric BPS quivers, non-isolated singularities, and deformations<\/strong><\/em><\/p>\n Toric quiver gauge theories describe the worldvolume dynamics of Dp-branes probing (3-complex dimensional) toric Calabi-Yau cones. About twenty years ago, the p=3 case was studied in depth due to its relevance to supersymmetric AdS_5\/CFT_4 dualities. More recently, the p=0 case has received interest as it encodes BPS particle excitations of 5-dimensional superconformal field theories on a circle. In this talk I will describe how non-isolated singularities in the geometry (and some of their deformations) impact the 5-dimensional SCFTs and their BPS quivers. If time allows, I will also make some comments on Higgs branch chiral rings of 5d SCFTs.<\/p>\n <\/p>\n Pablo Bueno<\/b> (Universitat de Barcelona) |\u00a0Quantum field theory from entanglement<\/strong><\/em><\/p>\n Growing evidence suggests that vacuum entanglement entropy (EE) may provide a universal description of QFT (in general dimensions), alternative to correlation functions. In this talk I will review the set of known axioms satisfied by EE in QFT and some of its successes in the direction of uniquely characterising the different models. Then, I will argue that such set of axioms is at present incomplete by explicitly showing that certain models which satisfy all the axioms do not correspond to any actual QFT.<\/p>\n Fridrich Valach<\/b> (Imperial College London) | Algebroids for membranes, strings, and particles<\/strong><\/em><\/p>\n I will discuss G-algebroids, structures related to various supergravities appearing in string and M-theory. I will describe some basic properties of these algebroids, present the main classification results, and show how they are useful for understanding Poisson-Lie U-duality and consistent truncations of 11D or 10D type IIA\/B supergravities. This is a joint work with M. Bugden, O. Hulik, and D. Waldram.<\/p>\n <\/p>\n Boris Pioline<\/b> (Paris, LPTHE) |\u00a0Counting Calabi-Yau black holes with (mock) modular forms<\/strong><\/em><\/p>\n Unlike in cases with maximal or half-maximal supersymmetry, the spectrum of supersymmetric black holes in type II string theory compactified on a Calabi-Yau threefold with generic SU(3) holonomy remains partially understood. Mathematically, the BPS indices counting these states coincide by the generalized Donaldson-Thomas invariants associated to the derived category of coherent sheaves, but they are rarely known explicitly. String dualities indicate that suitable generating series of rank 0 Donaldson-Thomas invariants counting D4-D2-D0 bound states\u00a0 should transform as vector-valued mock modular forms, in a very precise sense. I will spell out and test these predictions in the case of one-modulus compact Calabi-Yau manifolds (such as the quintic threefold), where the BPS indices can (at least in principle) be computed from Gopakumar-Vafa invariants, using recent mathematical results by S. Feyzbakhsh and R. Thomas.<\/p>\n Diego Rodriguez-Gomez<\/b> (Universidad de Oviedo) |\u00a0Field theory defects through double scaling limits<\/strong><\/em><\/p>\n Defect operators in field theory are very interesting for a number of reasons. Drawing inspiration from techniques which have been very recently applied to uncover interesting properties of sectors of operators with large charge under a global symmetry, we will study defects in the Wilson-Fisher fixed point near d=4,6 dimensions. Combining with localization, we will also use a double-scaling limit for certain Wilson loops in N=2 supersymmetric theories in 4d which allows to make exact statements at finite N.<\/p>\n <\/p>\n Lea Bottini<\/b> (University of Oxford) | Non-invertible symmetries and categorical structures<\/strong><\/em><\/p>\n Non-invertible symmetries in various dimensions have received a lot of attention recently. In this talk I will review some of their constructions and apply them to concrete gauge theory examples. I will also explain how in general the symmetries of a quantum field theory are described by a higher category and discuss some interesting phenomena that arise studying gaugings of symmetries in this context.<\/p>\n Jacopo Papalini<\/b> (INFN, Parma) | Nonperturbative aspects of JT gravity and TT deformation<\/strong><\/em><\/p>\n In this talk, I will investigate nonperturbative effects and phenomena occurring in low-dimensional gravity and gauge theories, both in presence and absence of integrable deformations.\u00a0 Specifically, I will concentrate on JT gravity, one of the rare examples of exactly solvable quantum gravity models, describing how the inclusion of nonperturbative completions is essential to render physical quantities well-definite, expecially when trying to extend the construction to higher-genus topologies in the gravitational path integral. For this purpose, I will then focus on the finite cutoff formulation of JT gravity, which from the holographic perspective is realized by a TT deformation of the dual Schwarzian theory on the asymptotic boundary.\u00a0 In the second part of the talk, I will introduce general properties of the TT deformation and move on by solving the emerging puzzling features about the deformed physical spectrum in the concrete case of TT-deformed Yang-Mills theory. I will derive the exact partition function for U(N) gauge group on the sphere topology, by studying the theory at the level of individual flux sectors. Finally, I will show how, in the large-N expansion, the theory exhibits an intriguing phase diagram where the transitions between different phases are driven by instantons both in the ‘t Hooft coupling and in the TT deformation parameter.<\/p>\n <\/p>\n Rishi Mouland<\/b> (Cambridge U., DAMTP) |\u00a0Black Holes in the Dual of Quantum Mechanics<\/strong><\/em><\/p>\n I will motivate and study a holographic duality between on one hand a theory of superconformal quantum mechanics, and on the other, M-theory on a particular background. I will exhibit a broad family of black hole solutions in the bulk theory, which fall into a wider class of \u201cultra-spinning\u201d black holes in various backgrounds. Through an asymptotic study of the superconformal index in the supergravity regime, I will provide a precise microstate counting for those ultra-spinning black holes that are supersymmetric. Finally, I will briefly discuss the relation of conformal quantum mechanics and ultra-spinning black holes to notions of holomorphic factorisation and gravitation blocks, for holographic CFTs in four and six dimensions.<\/p>\n Horatiu Nastase<\/b> (Sao Paulo, IFT) |\u00a0Learning from Penrose limits of less understood gravity dual pairs<\/strong><\/em><\/p>\n The Penrose limit of AdS\/CFT, giving the pp wave correspondence, simplifies the map between gravity dual pairs; in particular, one can usually quantize string eigenmodes. In the original application to AdS_5xS^5, one obtained a test of AdS\/CFT in a nontrivial regime. But it is also useful to apply the limit in order to better understand gravity dual pairs where the map, or the field theory, are less understood. I show results for the cases of the Guarino, Varela, Jafferis (GJV) duality, the T-dual of AdS_5xS^5, the Maldacena-Nastase (MNa) case and its T-dual.<\/p>\n <\/p>\n Luca Iliesiu<\/b>\u00a0(Stanford University) |\u00a0Indices from the gravitational path integral – new forms of attraction<\/em><\/strong><\/p>\n Recent results have revealed that black holes close to extremality experience large quantum corrections that drastically affect the black hole entropy at low temperatures. Because of this, all extremal solutions discussed in the past need to be reanalyzed. In this talk, I will explain how to understand the contributions to the gravitational partition function of two such solutions: the attractor solution and multi-center black hole solutions. Our new understanding leads to a new perspective on how the attractor mechanism can be understood at finite temperatures in Euclidean signature.<\/p>\n Oliver Janssen<\/b> (ICTP, Trieste) | Positivity in EFTs with spontaneously broken boosts<\/em><\/strong><\/p>\n We will discuss positivity bounds on EFT coefficients in theories where Lorentz boosts are spontaneously broken. The well-known S-matrix argument from the Lorentz-invariant scenario does not straightforwardly generalize to this case. Instead the analytic properties of the retarded Green\u2019s function of conserved currents will be used, and the theory will be assumed to become conformal in the UV. The method is general and applicable to both cosmology and condensed matter systems. As a concrete example we will consider the EFT of conformal superfluids, which describes the universal low-energy dynamics of CFTs at large U(1) charge, and we will derive inequalities on the coefficients of the operators, in three spacetime dimensions, at NLO and NNLO.<\/p>\n <\/p>\n Ivano Basile<\/b>\u00a0(ASC, Munich) |\u00a0SUSY-less AdS: braneworlds and scale separation<\/em><\/strong><\/p>\n Model building based on string compactifications faces difficult challenges at each step: moduli can be tricky to stabilize, scales to separate, dark energies to uplift and supersymmetry to break in a controlled fashion. String theories where the latter is broken at the string scale can offer different corners of the landscape to explore, with different pros and cons. I will describe how the instabilities of these models leave room for potentially realistic braneworld cosmologies, focusing on the simplest known examples.<\/p>\n Shani Meynet<\/b> (Uppsala University) |\u00a0McKay quivers, a physical perspective<\/strong><\/em><\/p>\n In this talk I will discuss McKay quivers and their application in theoretical physics. After a review of the main mathematical results, I will discuss their physical interpretation and, in particular, I will focus on two main aspects: the study of BPS states and higher form symmetries, in the context of geometric engineering, and the phenomenon of decomposition. Both of these aspects rely on the fact that the target space of the string sigma model is an orbifold of C^3 modded by a finite subgroup of SU(3), and thus can be studied in term of McKay quivers.<\/p>\n <\/p>\n Axel Kleinschmidt<\/strong> (AEI Potsdam) | BEL lecture<\/a>: String scattering old and new III<\/b> This lecture will discuss the systematics of low-energy expansions, first focussing on one-loop amplitudes and so-called modular graph functions and then on non-perturbative aspects and U-duality.<\/p>\n Emanuel Malek <\/b>(Humboldt-Universit\u00e4t zu Berlin) | Kaluza-Klein Spectrometry for String Theory Compactifications<\/p>\n I will present a powerful new method that for the first time allows us to compute the Kaluza-Klein spectrum of a large class of string theory compactifications. This includes geometries with little to no remaining (super-)symmetries, completely inaccessible by previous methods. I will show how these insights can be used to compute the anomalous dimensions of protected and unprotected operators in strongly-coupled CFTs, as well as to study global properties of their conformal manifolds. I will also show how the method can be used to determine the perturbative stability of non-supersymmetric AdS vacua. This reveals that tachyons can arise from higher Kaluza-Klein modes that are not visible in lower dimensions. Intriguingly, there are also classes of fully perturbatively stable non-supersymmetric AdS vacua in 10-d supergravity.<\/p>\n Axel Kleinschmidt\u00a0<\/strong>(AEI Potsdam) | BEL lecture<\/a>: String scattering old and new IV<\/b><\/em><\/strong><\/p>\n <\/p>\n24 May 2023, Brussels<\/h6>\n
\n17 May 2023, Leuven<\/h6>\n
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\n3 May 2023, Leuven<\/h6>\n
\n19 April 2023, Brussels<\/h6>\n
\n29 March 2023, Leuven<\/h6>\n
\n22 March 2023, Leuven<\/h6>\n
\n15 March 2023, Brussels<\/h6>\n
\n8 March 2023, Ghent<\/h6>\n
\n1 March 2023, Brussels<\/h6>\n
\n22 February 2023, Brussels<\/h6>\n
\n15 February 2023, Brussels<\/h6>\n
\n8 February 2023, Leuven<\/h6>\n
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\n<\/em><\/strong><\/p>\n1 February 2023, Mons<\/h6>\n
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