Timetable
| Monday | Tuesday | Wednesday | Thursday | Friday | |
| 9.30am | Registration | ||||
| 9.50am | Welcome | ||||
| 10am - 10.50am | Beisert | Vicedo | Ferko | Nuñez | Hulik |
| Break | Break | Break | Break | Break | |
| 11.10am - 12pm | Siampos | Levine | Caudrelier | Thompson | Osten |
| Lefundes | Shah | ||||
| 12pm | Closing | ||||
| Lunch | Lunch | Lunch | Lunch | Lunch | |
| 1.50pm - 2.40pm | Driezen | Yamazaki | Ekhammar | Gorbenko | Free Discussion |
| Break | Break | Break | Poster Session | ||
| 3pm - 3.50pm | Sfondrini | Chester | Bielli | ||
| Tsolakidis | |||||
| Break | Break | Break | |||
| 4.10pm - 5pm | IDD Discussion | Retore | Holguin | ||
| Scala | |||||
| Evening | Reception and Networking (5pm) | Conference Dinner (6pm) |
Registration and Research Talks on Monday, Tuesday, Wednesday and Friday will take place in Pärlan, Albano Campus House 1.
Research Talks on Thursday will take place in Lecture Room 32, Albano Campus House 4.
The Poster Session will include coffee and will take place in Nordita, Albano Campus House 3, floor 6.
The Zoom link to join online is:
https://epfl.zoom.us/j/66684192117?pwd=D1CYjT0F9BfSXLoLMSdLjdIcqmI7cM.1
Talks will also be streamed on YouTube at:
https://www.youtube.com/@intdualdef
Titles and Abstracts
Research Talks
Danielle Bielli (Chulalongkorn University) Slides Recording ↑
How helpful can an auxiliary field be?
Modifying Principal Chiral Models (PCMs) with the inclusion of auxiliary fields allows the construction of an infinite family of deformations which preserve integrability, extending TTbar and root-TTbar to deformations by arbitrary functions of the stress-tensor. This is achieved by trivially coupling the seed theory to the auxiliary fields, which are in turn characterised by an arbitrary interaction function E that only depends on the auxiliaries through certain specific combinations of them. I will try to highlight other benefits, and possible limitations, resulting from the inclusion of auxiliary fields, by discussing two applications of this framework: the non-Abelian T-dualisation of TTbar-like deformed PCMs and the construction of conserved local higher-spin currents driving Smirnov-Zamolodchikov-like flows in PCMs and various other classes of sigma models which can be deformed using this formalism.
Niklas Beisert (ETH Zurich) Slides Recording ↑
Yangian Symmetry for Twist-Deformed N=4 Gauge Theory
In this talk, I will discuss Yangian symmetry for planar twist-deformed N=4 gauge theory. Along the way, I will reconsider Yangian symmetry of the N=4 SYM action using variational forms. I will apply the results towards deducing Yangian symmetry in the fishnet limit.
Vincent Caudrelier (University of Leeds) Slides Recording ↑
Lagrangian multiforms: an action principle for integrability
Lagrangian and Hamiltonian formalisms have been developed and used for a long time. In integrable systems, the Hamiltonian formalism has been predominant in defining integrability, in term of (Poisson) commuting Hamiltonians. I will present the concept of Lagrangian multiforms and the associated variational principle as a framework that: 1) gives a purely variational criterion for integrability, 2) describes integrable hierarchies variationally. I will focus on how to construct Lagrangian multiforms that satisfy the equations in point 1) in order to fulfill point 2). This can be done by adapting to the variational language the powerful machinery of classical r-matrices which is known to underlie the strong connection between Liouville integrability and Lax pair integrability. It can also be done using geometric methods and ideas from gauge theories (cf Benoit Vicedo's talk). The talk will focus on finite dimensional systems for conciseness but I will show that the ideas extend easily to (ultralocal) 2D integrable field theories.
Shai Chester (Imperial College London) Slides Recording ↑
Virasoro-Shapiro amplitudes in AdS
The Virasoro-Shapiro (VS) amplitude describes closed string scattering at tree level in string theory, and is the most basic quantity in string theory. String theory is best understood in AdS background, where AdS/CFT gives a non-perturbative definition. But surprisingly the corresponding amplitude in AdS was not computed until recently, as worldsheet calculations are hard in the presence of Ramond-Ramond flux. We review the calculation of the AdS VS for AdS5 × S5 in an expansion around flat space, which follows from an ansatz for the amplitude in terms of a worldsheet integral of a special class of functions, combined with the block expansion of the flat space limit of the correlator in the dual CFT. We then generalize this calculation to AdS4 × CP3 and AdS3 × S3 × K3 and AdS3 × S3 × T4. Our results give predictions for CFT data of heavy single trace operators, e.g. the Konishi, that can be compared to integrability.
Sibylle Driezen (ETH Zurich) Slides Recording ↑
Jordanian-twisted strings and spins
I will present recent work on new integrable structures arising from twist-deformations of the spin-chain formulation of the AdS_5 x S^5 superstring. My focus will be on Drinfel’d twists of the Jordanian type, which should entail spin-chain avatars of worldsheet non-Abelian T-duality. While the corresponding string sigma-model is known to be Lax integrable it exhibits particle production, raising fundamental questions about the scope and fate of its integrability-based studies. From the spin-chain perspective, however, we show that a different picture emerges: the natural eigenstates of the Jordanian model are not organised by particle number but by a non-Cartan residual symmetry. In this basis we then find that the spectrum follows from a remarkably simple Baxter equation. This further provides us with first evidence for a non-abelian deformed AdS/CFT through an explicit match with the energy of the (semi-)classical string.
Simon Ekhammar (King's College London) Slides Recording ↑
Asymptotic Baxter-Bethe Ansatz for Regge Trajectories
Maximally supersymmetric four-dimensional Yang-Mills appear to be solvable in the planar limit. In particular, the non-perturbative spectrum of local operators can be calculated using the integrability-based Quantum Spectral Curve (QSC) formalism. However, the usefulness QSC extends beyond local operators. I will demonstrate how it can be used to understand what happens upon analytic continuation to negative spin, into the regime of horizontal Regge trajectories. Taking a weak coupling limit I will formulate a novel ”Asymptotic Baxter-Bethe Ansatz”: a set of equations, reminiscent of the Beisert-EdenStaudacher equations, that controls the trajectories.
Christian Ferko (Northeastern University, Boston) Slides Recording ↑
Soliton Surfaces and the Geometry of Integrable Deformations of the CPN-1 Model
In this talk, I will present a geometrical interpretation of the recently-introduced integrable auxiliary field deformations of sigma models. Focusing on the CPN-1 model, a special case of a symmetric space sigma model (SSSM) that shares several properties with 4d Yang-Mills theory, I will describe the modifications to the Sym-Tafel soliton surface (which recasts aspects of the integrable structure of the theory in geometrical form) that occur when one implements auxiliary field deformations. Finally, I will explain that auxiliary field deformations of general SSSMs can be understood geometrically as either (a) coupling the undeformed theory to a field dependent metric, or (b) making a particular non-trivial choice of "moving frame" on the soliton surface.
Victor Gorbenko (EPFL, Lausanne) Slides Recording ↑
Quantum group as a global symmetry
I will discuss quantum field theories that have quantum group as a global internal symmetry. I will show that quantum groups act naturally on defect ending operators and even can transform a local operator into a defect ending one. I will focus on a particular solvable 2D CFT where the symmetry generators can be constructed explicitly and show that various consequences of the symmetry, like Ward identities, are indeed satisfied. I will then present some numerical checks of our computations using a related spin-chain model, and finally consider a non-integrable deformation of the model that still preserves the QG symmetry, but which spectrum is chaotic.
Adolfo Holguin (Trinity College Dublin) Slides Recording ↑
(Un)solvable Matrix Models for BPS correlators
BPS states in superconformal gauge theories are a simple playground for understanding the large N limit of heavy operators. I will discuss recent progress on protected correlators of operators of dimension N (N^2) in maximally supersymmetric Yang-Mills. For the case of half-BPS operators, I will present solvable matrix models that compute two and three point correlation functions and explain how to reconstruct their geometric dual. In particular I will show how to compute vevs of all single trace half-BPS operators in general half-BPS backgrounds in agreement with holographic calculations, and vevs of 'giant' operators dual to branes. I will comment on (unsolvable!) generalizations to less supersymmetric states and their connection to quenched lattice models.
Ondřej Hulik (Heidelberg University) Slides Recording ↑
Ricci flat metrics from GLSM with a shadow, and generalized CY ansatz
GLSM models describe a large class of interesting geometries as symplectic quotients. However, they generally cannot produce a Ricci-flat metric on the quotient space. I will present a new construction/extension of standard GLSM techniques that circumvents this problem. Furthermore, using toric geometry, I will explain how this method is related to the Calabi–Yau ansatz known in the literature.
Gabriel Lefundes (IPhT, Saclay) Slides Recording ↑
Wrapping the (twisted) pair of pants
A particular quiver N=2 superconformal field theory (SCFT) can be obtained through a Z_K orbifold projection of N=4 SYM. In this talk, I will explain how to implement twists within the hexagonalization framework to compute three-point functions of Coulomb branch operators in this theory. Our results match exact expressions derived from supersymmetric localization, which take the form of Fredholm determinants. A central challenge in this approach is the proper regularization of decoupling poles, which is essential for correctly capturing the so-called wrapping effects.
Nat Levine (University of Amsterdam) Slides Recording ↑
Demystifying integrable QFTs in AdS: No-go theorems for higher-spin charges
Higher-spin conserved charges feature prominently in integrable 2d QFTs in flat space. Motivated by the question of integrable field theories in AdS space, we consider the consequences of higher-spin charges for QFTs in AdS_2. We find that their effect is much more constraining than in flat space. Specifically, it is impossible to preserve: (a) any higher-spin charges when deforming a massive free field by interactions, or (b) any spin-3 charges when deforming a CFT by a Virasoro primary. Therefore, in these settings, there are no integrable theories in AdS with higher-spin conserved charges.
Carlos Nuñez (Swansea University) Slides Recording ↑
Aspects of gauge-strings duality
I will discuss (hopefully in pedagogical manner), some recent developments in the duality between gauge fields and strings.
I will try to discuss some developments around systems that present confinement and screening. The talk is based on the papers I wrote in the last seven months.
David Osten (University of Wrocław) Slides Recording ↑
An integrable sector of the membrane
In contrast to string sigma models which are well-known to be (classically) integrable in certain backgrounds, most famously flat space or AdS5 × S5, the same is not true for the membrane sigma model. Reasons for this are the non-trivial gravity on the world-volume but also the rarity of three-dimensional integrable field theories in general.
Here, I will present the novel observation that a decoupling limit of the membrane in certain backgrounds will lead to an integrable model, the Manakov-Zakharov-Ward model -- a known three-dimensional, but non-Lorentzian, integrable field theory. An example of backgrounds in which this limit is possible is the 11d uplift of the pure NS-NS AdS3 × S3 × T4 background.
Ana Retore (DESY Hamburg) Slides Recording ↑
Spin-1 isotropic chains beyond nearest-neighbor interactions
Three distinct integrable spin-1 chains with su(2) symmetry are known, each described by a Hamiltonian involving only nearest-neighbor (NN) interactions. In this talk, I will present a systematic framework for constructing long-range deformations of NN spin chains and show its application to these models.
Luca Scala (University of Wrocław) Slides Recording ↑
α'-corrections from Maxwell∞ deformations
Computing high-order alpha'-corrections to the low energy limit of string theories is a challenging matter. Usually, this calculation is performed by means of string scattering amplitudes, and due to its complexity only a few non-trivial orders appeared in literature to the present day. Recently, a new approach starting from generalised geometry and building on the work of Polacek and Siegel was proposed. This method employs tools from Cartan geometry to describe a hidden spontaneously broken symmetry of string theories that might be the key to understand the structure of the alpha'-expansion without explicitly compute scattering amplitudes. A key role in this approach seems to be played by a deformation of a subalgebra of the extended Maxwell-infinity one.
Parita Shah (SUNY, Albany) Slides Recording ↑
Double Field Theory and α′-corrections
The Double Field Theory effective actions are naturally written in terms of modified connections and curvatures with torsion to incorporate α′-corrections. I will talk about how we can construct the most general solutions with vanishing modified torsion, and such geometries that do not receive quantum corrections. I will also talk about obtaining corrections to several supergravity solutions, including a pair of geometries related by a non–abelian T-duality.
Alessandro Sfondrini (University of Padova) Slides Recording ↑
Understanding AdS3/CFT2: Successes and Challenges
In the last few years there has been remarkable progress in understanding the AdS3/CFT2 duality by CFT and integrability techniques. I will give a non-technical overview of this progress, focusing on the case of strings on AdS3xS3xT4 supported by NSNS, RR, or mixed NSNS/RR fluxes.
Konstantinos Siampos (Aristotle University of Thessaloniki) Slides Recording ↑
Scale without conformal invariance from integrable deformations of coset CFTs
We consider integrable \lambda deformation of coset CFTs that interpolate between gauge WZW model of symmetric coset CFTs and non-Abelian T-dual of PCMs. As an example we study the \lambda-deformed SU(2)/U(1) model which is integrable and renormalizable. Under an analytic continuation and an appropriate asymptotic limit, we uncover a model which is scale-invariant but not conformally invariant at one-loop order bypassing Polchinski’s no-go theorem. Its target spacetime describes a two-dimensional scale invariant black hole, corresponding to a Kerr-Schild deformation of the underlying coset CFT SL(2,R)/SO(2), and we provide embeddings to type-II supergravity. We extend the above results for the \lambda model on SU(3)/U(2) and SU(1,2)/U(2). Considering an asymptotic double-scaling limit of SU(1,2)/U(2), we recover a scale invariant two-dimensional field theory whose deformation does not admit a Kerr-Schild form, unlike the the SL(2,R)/SO(2) case.
Dan Thompson (Swansea University) Board Talk Recording ↑
Diamond Gauging Redux
I will revisit the role of Chern–Simons theory in the construction of integrable sigma models, focusing on how gauged deformations can be reformulated in a more geometric fashion. Building on the 6d Chern–Simons origin of ungauged deformations and earlier work on the gauged case, I will present a unified framework based on bundle reductions and transgression forms. This perspective provides a natural splitting of gauge fields, clarifies the emergence of tensorial degrees of freedom, and leads directly to the λ-deformed gWZW model. The framework suggests new ways to organise integrable deformations and may open avenues for generalisations beyond the known cases.
Evangelos Tsolakidis (University of Iceland) Slides Recording ↑
TTbar deformations in any d
I will present a simple yet powerful gravitational framework for stress tensor deformations of quantum field theories in any dimension, based on the two dimensional massive gravity description of TTbar. As a direct consequence, a unique higher-dimensional operator makes its appearance, matching and extending previous results coming from AdS/CFT. The dual gravitational model to that operator is found to be a well-known, ghost-free massive gravity theory.
Benoît Vicedo (University of York) Slides Recording ↑
A variational formulation of the Hitchin system
I will present a variational formulation of the Hitchin system on a compact Riemann surface C of arbitrary genus, allowing simple poles in the Higgs field at finitely many points. The hierarchy of time flows is described within the framework of Lagrangian multiforms, which I will briefly review. Adapting Hitchin’s construction — via symplectic reduction of the space of stable holomorphic structures on a principal G-bundle P \to C — to this variational setting naturally produces a multiform version of the action of 3d mixed BF theory with defects, a lower-dimensional analogue of the celebrated 4d semi-holomorphic Chern–Simons theory. Working directly in holomorphic local trivialisations of principal G-bundles yields a simple 1d action that unifies several well-known integrable hierarchies — rational and elliptic Gaudin, including elliptic spin Calogero–Moser — within a single variational framework. This is based on [arXiv:2509.05127] with V. Caudrelier, D. Harland and A. A. Singh.
Masahito Yamazaki (Kavli IPMU Tokyo) Slides Recording ↑
TTbar and root-TTbar deformations in four-dimensional Chern-Simons theory
We study TTbar and root-TTbar deformations of two-dimensional integrable field theories within the framework of four-dimensional CS theory coupled to disorder defects.
Posters ↑
Hank Chen (Beijing Institute of Mathematical Sciences and Applications) Poster
Higher-Integrability from Derived Kac-Moody algebras and the Affine Raviolo VOA
Lewis Cole (University of Edinburgh) Poster
Holomorphic-Topological Field Theories and Higher-Dimensional Integrability
Zhengyuan Du (Tsinghua University) Poster
Symmetry and Operators in TTbar-deformed CFT
Miguel Garcia Fernández (University of Santiago de Compostela) Poster
Jordanian deformation of the XXX_{-1/2} spin chain
Rashad Hamidi (Durham University) Poster
Integrable 2d trigonometric ZN-twisted σ-models
Steven Weilong Hsia (Masaryk University) Poster
No Manifest T-duality at α'^3
Adrien Molines (ETH Zurich) Poster
The Jordanian Twisted sl(2,R) Spin Chain
Alexia Nix (University of Iceland) Poster
N=2 Chern-Simons matter theories and Precision Holography
Xin Qian (University of Copenhagen) Poster
Spectrum in defect ABJM theory
Alex Swash (University of Wrocław) Poster
Gauged Extended Field Theory and Generalised Cartan Geometry
Anders Wallberg (EPFL, Lausanne) Poster
1-loop renormalisability of integrable sigma-models from 4d Chern-Simons theory
Aleksandr Zhabin (EPFL, Lausanne) Poster
Quantum Group as a Global Symmetry
