Time in CEST |
Monday |
Tuesday |
Wednesday |
Thursday |
Friday |

09:30 - 10:15 |
Registration | Free Discussion | Free Discussion | Free Discussion | Free Discussion |

10:15 - 11:15 |
Konstantin Zarembo |
Jia Tian |
Patrick Dorey |
Olaf Hohm |
Yannik Zimmermann |

11:15 - 12:00 |
Coffee Break |
Coffee Break |
Coffee Break |
Coffee Break |
Coffee Break |

12:00 - 13:00 |
Gleb Kotousov |
Konstantinos Siampos |
Leander Wyss |
Daniel Waldram |
Gleb Arutyunov |

13:00 - 15:00 |
Lunch Break |
Lunch Break |
Lunch Break |
Lunch Break |
Lunch Break |

15:00 - 16:00 |
Alessandro Sfondrini |
Benoît Vicedo |
Alexey Litvinov |
Linus Wulff |
Free Discussion |

16:00 - 16:45 |
Coffee Break |
Coffee Break |
Coffee Break |
Coffee Break |
Coffee Break |

16:45 - 17:45 |
Benjamin Basso |
David Osten |
Ana L. Retore |
Patrizia Vitale |
Free Discussion |

Key |
In-person Talk |
Virtual Talk |
Administration and Discussion | Breaks |

**Gleb Arutyunov**^{@} (Hamburg U. and DESY) slides - recording

* Title: *New integrable coset sigma models

* Abstract: *By using the general framework of affine Gaudin models, I present a construction of a new class of integrable sigma models and discuss particularly interesting examples.

**Benjamin Basso** (LPENS, Paris) slides - recording

* Title:* On the wrapping problem for structure constants in planar N=4 SYM

* Abstract:* I will talk about the calculation of 3pt functions of single-trace operators in planar N=4 SYM using the hexagon form factor expansion. The method is well known to encounter difficulties for short operators, with wrapping divergences plaguing the formalism. I will explain how to renormalize these divergences away in simple set ups and explore the resulting pattern of finite-size corrections. In particular, I will unveil a new type of finite-size corrections - the cubic wrapping - which helps resolving discrepancies with string and gauge theory at strong and weak coupling. If time permits, I will present a conjecture that incorporates the infinite tower of wrapping corrections for the simplest structure constants in the form of "simple" dressing factors. Based on work in progress with Alessandro Georgoudis.

**Patrick Dorey** (Durham U.) slides - recording

* Title:* Breaking integrability in classical field theories

* Abstract: *This talk will survey the surprisingly complicated way that particle-like excitations in non-integrable field theories can scatter. The story has a long history but new phenomena are still being discovered, and many of the most interesting examples come from cases when the breaking of integrability appears to be very mild.

**Olaf Hohm ^{@}** (Humboldt U. Berlin) slides - recording

* Title:* Duality and Higher Derivatives

* Abstract: *I review recent work on the interplay of higher-derivative \alpha' corrections in string theory and the duality symmetries that arise upon dimensional reduction, notably the group O(d,d,R), which is known to be preserved to all orders in \alpha' but whose explicit realization has only been explored recently.

**Gleb Kotousov** (DESY) slides - recording

* Title: *Generalized affine sl(2) Gaudin model

* Abstract: *The talk is based on the recent work arXiv:2106.01238, where a multiparametric integrable system is introduced and studied. The model encompasses some well known theories such as the quantum KdV integrable structure, and can be thought of as a generalization of the affine sl(2) Gaudin model. The construction of the local Integrals of Motion, following the usual procedures in Yang-Baxter integrability, is discussed. In addition, the ODE/IQFT correspondence for the model is presented. The talk is framed within the context of the quantization of non-ultralocal integrable field theories such as the O(N) models.

**Alexey Litvinov ^{@}** (Landau Inst. and Skoltech) slides - recording

* Title:* Affine Yangian of gl(2) and integrable structure of superconformal field theory

* Abstract:* We study integrable structures of superconformal field theory and more general coset CFT's related to the affine Yangian Y(gl(2)). We derive the relation between the RLL and current realizations of Y(gl(2)) and prove Bethe anzatz equations for the spectrum of Integrals of Motion.

**David Osten** (ITMP, Moscow) slides - recording

* Title: *Exceptional world-volume currents and their algebras

* Abstract: *Motivated by the E-model formulation of a string sigma model, that turned out to be useful for the study of classical integrability and Poisson-Lie T-duality, a classical E(d(d))-invariant Hamiltonian formulation of world-volume theories of the typical p-branes in type IIb and eleven-dimensional supergravity is proposed, extending known results up to d=6.

This formulation consists of a Hamiltonian, characterised by a generalised metric, and a current algebra constructed s.t. it reproduces the E(d(d)) generalised Lie derivative. In this talk I will, starting from a review of the well-known O(d,d)-case of that construction -- the E-model --, discuss the M2-brane in the SL(5)-theory before, motivated by that, introduce the general case. Also the possibilities of deriving the current algebra from a canonical Poisson structure, and the connection of the latter to para-Hermitian exceptional geometry is discussed. This talk is based on arXiv:2103.03267 and ongoing work.

**Ana L. Retore** (Trinity Coll., Dublin) slides - recording

* Title: *New integrable deformations for AdS2 and AdS3 R-matrices

* Abstract: *In this talk I will present new integrable deformations of AdS2 and AdS3 R-matrices. I will explain the new method to find solutions of Yang-Baxter equation which we applied to construct these deformations as well as explain some of its properties and symmetries.

***Hubert Saleur ^{@}** (IPhT Saclay and Southern California U.)

* Title:*The O(n) and Q-state Potts model CFTs in 2D - the conclusion of a long story?

* Abstract:* I will discuss new results about the CFT description of 2D bulk O(n) and Q-state Potts models (and their self-avoiding walks and percolation limits). These results follow from the convergence of several approaches, including exact lattice calculations, representation theory, and the bootstrap.

**Alessandro Sfondrini **(Padova U.) slides - recording

* Title: *AdS3 correlation functions from integrability

* Abstract: *Computing non-protected observables in AdS/CFT in presence of RR background fluxes is notoriously hard. For the spectrum of integrable backgrounds, the mirror TBA / QSC provide a framework for doing so. For correlation functions, the hexagon formalism is a promising approach but was only developed for AdS5xS5. Here we show how it can be generalised to AdS3xS3xT4 backgrounds which can be supported by a mixture of RR and NSNS fluxes. This provides a new playground for understanding these backgrounds and, when focusing on the pure-NSNS limit, an important benchmark for the hexagon formalism since in that limit alternative worldsheet CFT techniques become available.

**Konstantinos Siampos** (National and Kapodistrian University of Athens) slides - recording

* Title:* Integrable deformations and asymptotic limits

* Abstract:* We construct a new class of integrable \sigma-models which interpolate under the RG flow between exact coset CFTs in the IR and hyperbolic spaces in the UV. We explore their relationship to the asymptotic limit of \lambda-deformed models for cosets of non-compact groups. We also uncover an integrable model which interpolates under the RG flow between two exact CFTs of a cosmological and a black hole interpretation in the IR and UV fixed points. Finally, we consider Kerr-Schild deformations of coset CFTs which lead to a novel class of scale invariant \sigma-models that also preserve integrability. These models can be also obtained by taking appropriate asymptotic limits of \lambda-deformed coset CFTs.

**Jia Tian ^{@}** (Peking U.) slides - recording

* Title: *Deformed Integrable Models from Holomorphic Chern-Simons Theory

* Abstract: *We study the approaches to two-dimensional integrable field theories via a six-dimensional (6D) holomorphic Chern-Simons theory defined on twistor space. Under symmetry reduction, it reduces to a four-dimensional Chern-Simons theory, while under solving along fibres it leads to four-dimensional (4D) integrable theory, the anti-self-dual Yang-Mills or its generalizations. From both four-dimensional theories, various two-dimensional integrable field theories can be obtained. In this work, we try to investigate several two-dimensional integrable deformations in this framework. Based on arXiv:2105.06826.

**Benoît Vicedo ^{@}** (York U.) slides - recording

* Title:* Non-ultralocality, affine Gaudin models and ODE/IM

* Abstract:* The spectrum of the Gaudin model associated with a finite-dimensional semisimple Lie algebra is well known to be described in terms of certain ordinary differential operators, known as opers, associated with the Langlands dual Lie algebra. In this talk I will review attempts at understanding the ODE/IM correspondence as a generalisation of this Gaudin/oper correspondence to the setting of affine Kac-Moody algebras and explain the connection to the problem of quantisation of non-ultralocal classical integrable field theories.

**Patrizia Vitale** (INFN Naples) slides - recording

* Title: *Topological and dynamical aspects of Jacobi sigma models

* Abstract: *The geometric properties of sigma models with target space a Jacobi manifold will be illustrated. Jacobi sigma models are topological field theories, which share and generalize relevant features of Poisson sigma models, such as gauge invariance under diffeomorphisms and finite dimension of the reduced phase space. Besides first class constraints, which generate gauge transformations, second class constraints are present, which make the analysis of the reduced phase space different from the Poisson sigma model. Contact as well as locally conformal symplectic target spaces will be described, as main instances of Jacobi sigma models.

**Daniel Waldram ^{@}** (Imperial College London) slides - recording

* Title:* Consistent truncations, Poisson-Lie U-duality and G-algebroids

* Abstract:* “G-algebroids” are natural extension of Lie and Courant algebroids that give a unified picture of the symmetries that underlie generalised and exceptional geometry as well as new “non-exact” versions. We analyse their structure in the exceptional case, and translate the problem of finding maximally supersymmetric consistent truncations of supergravity into a simple set of algebraic conditions. We show how generic Poisson-Lie U-duality is encoded in this framework and prove, in particular, that it is compatible with the supergravity equations of motion.

**Linus Wulff** (Masaryk U. Brno) slides - recording

* Title: *O(d,d) and \alpha'-corrections

* Abstract: *Tree-level string theory on backgrounds with d commuting isometries features a continuous O(d,d) symmetry. I will discuss some attempts to use this symmetry to determine the explicit form of higher-derivative alpha'-corrections to the effective action, in particular the completion of the Riemann^4 terms.

**Leander Wyss** (Surrey U.) slides - recording

* Title: *Boost superalgebras in undeformed and deformed AdS_3/CFT_2

* Abstract: *In this talk, I will present our results on the modified Poincaré algebra that can be found in the framework of the massless AdS_3/CFT_2 scattering problem. The R-matrices associated to it present some interesting behaviour with respect to the boost generator of said algebra. A similar connection appears in the q-deformed case, where we also found some curious non-associative structures. Finally, I will talk about the coproducts of the boost operator and establish a classification of boost algebras and coproducts in a universal, representation-independent sense, where we arrive at six different algebraic structures. Finally, we will investigate and discuss what is still unknown for some of the deformed contexts we are currently working on.

**Konstantin Zarembo** (NORDITA) slides

* Title: *Integrable D-branes

* Abstract: *Integrable boundary states arise if AdS/CFT deformed by a D-brane. In the dual Yang-Mills theory D-branes describe a number of set-ups (spontaneous symmetry breaking, very heavy operators, etc), and allows for systematic calculation of the simplest correlators, the one-point functions. I will concentrate on the defect CFT with a domain wall, dCFT, and will discuss how the one-point functions transform under bosonic and fermionic dualities of the underlying integrable system.

**Yannik Zimmermann** (Humboldt U. Berlin) slides - recording

* Title:* Do Drinfeld twists survive quantization?

* Abstract: *Under a homogeneous Yang-Baxter deformation the symmetry algebra of stringy sigma models is expected to be Drinfeld twisted. We check this expectation for a collection of Abelian Yang-Baxter deformations of the AdS5xS5 string at the quantum level by calculating the tree-level scattering matrices. They exhibit the expected Drinfeld-twisted structure, except for cases in which the deformation interacts non-trivially with the light-cone gauge.

**@** virtual talk, * cancelled