BEGIN:VCALENDAR VERSION:2.0 PRODID:researchseminars.org CALSCALE:GREGORIAN X-WR-CALNAME:researchseminars.org BEGIN:VEVENT SUMMARY:Dmytro Volin (Nordita) DTSTART:20200507T090000Z DTEND:20200507T110000Z DTSTAMP:20260422T230723Z UID:LIJC/1 DESCRIPTION:Title: Com pleteness of Bethe equations\nby Dmytro Volin (Nordita) as part of Lon don Integrability Journal Club\n\n\nAbstract\nWe review a proof of bijecti on between eigenstates of the Bethe algebra and solutions of Bethe equatio ns written as a Wronskian quantisation condition or as QQ-relations on You ng diagrams. Furthermore\, it is demonstrated that the Bethe algebra is ma ximal commutative and it has simple spectrum every time it is diagonalisab le. The proof covers rational gl(m|n) spin chains in the defining represe ntation with the famous Heisenberg spin chain being a particular subcase. The proof is rigorous (no general position arguments are used). We do not rely on the string hypothesis and moreover we conjecture a precise meanin g of Bethe strings as a consequence of the proposed proof.\nA short introd uction with necessary facts about polynomial rings will be given at the be ginning of the talk. \nBased on 2004.02865\n LOCATION:https://researchseminars.org/talk/LIJC/1/ END:VEVENT BEGIN:VEVENT SUMMARY:Shota Komatsu (IAS) DTSTART:20200515T130000Z DTEND:20200515T150000Z DTSTAMP:20260422T230723Z UID:LIJC/2 DESCRIPTION:Title: Wil son loops as matrix product states\nby Shota Komatsu (IAS) as part of London Integrability Journal Club\n\n\nAbstract\nIn his paper in 1979\, Po lyakov envisaged a possibility of reformulating the gauge theory as a Prin cipal Chiral Model defined on a space of loops and discussed "the loop-spa ce integrability". This idea\, together with a closely related idea of the loop equation\, led to numerous important results in matrix models and 2d gauge theories\, but its application to four-dimensional gauge theories h ad only limited success. Now\, after 50 years\, we have a concrete example of integrable four-dimensional gauge theory\, N=4 SYM. However integrabil ity in N=4 SYM is formulated mostly in terms of local operators\, although important progress has been made in constructing the Yangian for the Wils on loops. In this talk\, I will present a framework which would bridge the se two distant notions of integrabililty. The key player in the story is a correlation function of a local operator and the Wilson loop. I reformula te the gauge-theory computation of this observable as an overlap between a n energy eigenstate of a spin chain and a matrix product state (MPS). Unli ke standard MPS's discussed in the literature\, our MPS has infinite bond dimensions in order to accommodate infinite dimensionality of the space of loops. It provides an "intertwiner" between integrable structures of the local operators and the Wilson loops\, and in particular implies the exist ence of a special set of deformations of the Wilson loop which satisfy the QQ-relation. I will also explain how to formulate a nonperturbative boots trap program based on the results obtained in this framework and compute t he correlator of the circular BPS Wilson loop and general non-BPS operator s at finite coupling\, emphasizing the relation to and the difference from other observables that were computed by a similar approach.\n LOCATION:https://researchseminars.org/talk/LIJC/2/ END:VEVENT BEGIN:VEVENT SUMMARY:Ines Aniceto (Southampton U) DTSTART:20200521T130000Z DTEND:20200521T150000Z DTSTAMP:20260422T230723Z UID:LIJC/3 DESCRIPTION:Title: Int egrable Field Theories with an Interacting Massless Sector\nby Ines An iceto (Southampton U) as part of London Integrability Journal Club\n\n\nAb stract\nIntegrability techniques have played a major role in the study the AdS/CFT correspondence\, providing an accurate description of different s tring theoretic observables beyond the weak or strong coupling perturbati on theory. However\, the case of string on certain $AdS_3$ backgrounds pro vided new challenges in the form of massless excitations. Difficulties in incorporating these into the integrable description have led to disagreeme nts concerning the energy of massive physical states. \nIn general integra ble theories\, massless and massive sectors can generally be treated separ ately. We know this cannot be the case in $AdS_3$\, but a full TBA descrip tion of the interaction between the sectors is yet to be found. Surprising ly\, such a description can found in a family of integrable field theories — homogeneous sine-Gordon models. Here\, one can take a double scaling limit of the adjustable parameters and zoom into a regime described by a TBA where the massless sector does not decouple and contributes to the ene rgy of massive particles at the same order as for which the Bethe ansatz w ould suffice in a massive theory.\n\nannouncements also on https://integra bility-london.weebly.com/\n LOCATION:https://researchseminars.org/talk/LIJC/3/ END:VEVENT BEGIN:VEVENT SUMMARY:Tamas Gombor (Wigner Research Centre for Physics) DTSTART:20200528T130000Z DTEND:20200528T150000Z DTSTAMP:20260422T230723Z UID:LIJC/4 DESCRIPTION:Title: Bou ndary states\, overlaps\, nesting and bootstrapping AdS/dCFT\nby Tamas Gombor (Wigner Research Centre for Physics) as part of London Integrabili ty Journal Club\n\n\nAbstract\nRecently there have been renewed interest a nd relevant progress in calculating overlaps between periodic multiparticl e states and integrable boundary states. They appear in quite distinct par ts of theoretical physics including statistical physics and the gauge/str ing duality.\nI will give a summary of known overlap formulas and analyze the connection between selection rules and symmetries. I will introduce a nesting procedure for boundary states which provides the factorizing overl aps for higher rank algebras automatically. This method can be used for th e calculation of the asymptotic all-loop 1-point functions in AdS/dCFT. In doing so I will present the solutions of the YBE for the K-matrices with centrally extended su(2|2) symmetry and the generic overlaps of the corres ponding boundary states.\nBased on 2004.11329\n LOCATION:https://researchseminars.org/talk/LIJC/4/ END:VEVENT BEGIN:VEVENT SUMMARY:Olof Ohlsson Sax (Nordita) DTSTART:20200604T140000Z DTEND:20200604T160000Z DTSTAMP:20260422T230723Z UID:LIJC/5 DESCRIPTION:Title: Cro ssing equations for mixed flux AdS3/CFT2\nby Olof Ohlsson Sax (Nordita ) as part of London Integrability Journal Club\n\n\nAbstract\nI will give an overview of recent progress in understanding string theory in AdS3 back grounds with a mixture of\nRamond-Ramond and Neveu-Schwarz-Neveu-Schwarz t hree-form flux. Such theories are integrable\, but provide many features\n not encountered in the more familiar case of pure Ramond-Ramond flux. In t his talk I will explore the analytic structure\nof the dispersion relation of the world-sheet excitations and how it relates to the crossing equatio ns of the\ntwo-particle S matrix. Determining the dressing phases of the m ixed flux S matrix is the next major step in using\nintegrability to the A dS3/CFT2 correspondence.\n LOCATION:https://researchseminars.org/talk/LIJC/5/ END:VEVENT BEGIN:VEVENT SUMMARY:Gwenael Ferrando (Ecole Normale Superieure) DTSTART:20200611T140000Z DTEND:20200611T160000Z DTSTAMP:20260422T230723Z UID:LIJC/6 DESCRIPTION:Title: Fis hnet CFT: TBA and Non-compact Spin Chain\nby Gwenael Ferrando (Ecole N ormale Superieure) as part of London Integrability Journal Club\n\n\nAbstr act\nThe fishnet CFT is a non-unitary CFT of two matrix complex scalar fie lds interacting via a single quartic potential. The chiral nature of the i nteraction strongly constrains the Feynman diagrams arising at each order in perturbation theory\, those that survive are of fishnet type. In this t alk\, I will present the TBA equations for the conformal dimensions of mul ti-magnon local operators in this theory. I will emphasize the need to dia gonalize suitable graph-building operators in order to determine the asymp totic data\, dispersion relation and S matrix\, on which the TBA relies. A dual version of the TBA equations\, relating D-dimensional graphs to two- dimensional sigma models\, will also be examined. The last part of the tal k will be devoted to the presentation of the underlying non-compact spin c hain and of additional results regarding diagonalization of graph-building operators.\n LOCATION:https://researchseminars.org/talk/LIJC/6/ END:VEVENT BEGIN:VEVENT SUMMARY:Carlo Meneghelli (Oxford) DTSTART:20200723T140000Z DTEND:20200723T160000Z DTSTAMP:20260422T230723Z UID:LIJC/7 DESCRIPTION:Title: Pre -fundamental representations for the Hubbard model and AdS/CFT\nby Car lo Meneghelli (Oxford) as part of London Integrability Journal Club\n\n\nA bstract\nThere is a class of representations of quantum groups\, referred to as prefundamental representations\, that plays an important role in the solution of integrable models. The first example of such representations was given by V. Bazhanov\, S. Lukyanov and A. Zamolodchikov in the context of two dimensional conformal field theory in order to construct Baxter Q- operators as transfer matrices. At the same time\, there is a rather excep tional quantum group that governs the integrable structure of the one dime nsional Hubbard model and plays a fundamental role in the AdS/CFT correspo ndence. In this talk I will introduce prefundamental representations for t his quantum group\, explain their basic properties and discuss some of the ir applications.\n LOCATION:https://researchseminars.org/talk/LIJC/7/ END:VEVENT BEGIN:VEVENT SUMMARY:Joao Caetano (YITP) DTSTART:20200625T140000Z DTEND:20200625T160000Z DTSTAMP:20260422T230723Z UID:LIJC/8 DESCRIPTION:Title: Exa ct g-functions\nby Joao Caetano (YITP) as part of London Integrability Journal Club\n\n\nAbstract\n​The g-function is a measure of degrees of freedom associated to a boundary of two-dimensional quantum field theories . In integrable theories\, it can be computed exactly in a form of the Fre dholm determinant\, but it is often hard to evaluate numerically. In this paper\, we derive functional equations---or equivalently integral equation s of the thermodynamic Bethe ansatz (TBA) type---which directly compute th e g-function in the simplest integrable theory\; the sinh-Gordon theory at the self-dual point. The derivation is based on the classic result by Tra cy and Widom on the relation between Fredholm determinants and TBA\, which was used also in the context of topological string. As a side result\, we present multiple integrals of Q-functions which we conjecture to describe a universal part of the g-function\, and discuss its implication to integ rable spin chains.\n LOCATION:https://researchseminars.org/talk/LIJC/8/ END:VEVENT BEGIN:VEVENT SUMMARY:Marius de Leeuw DTSTART:20200709T140000Z DTEND:20200709T160000Z DTSTAMP:20260422T230723Z UID:LIJC/10 DESCRIPTION:Title: So lving the Yang-Baxter equation\nby Marius de Leeuw as part of London Integrability Journal Club\n\n\nAbstract\nThe Yang-Baxter equation is an i mportant equation that appears in many\ndifferent areas of physics. It sig nals the presence of integrable\nstructures which appear in topics ranging from condensed matter physics\nto holography. In this talk I will discuss a new method to find all\nregular solutions of the Yang-Baxter equation b y using the so-called\nboost automorphism. The main idea behind this metho d is to use the\nHamiltonian rather than the R-matrix as a starting point. I will\ndemonstrate our method by classifying all solutions of the Yang-B axter\nequation of eight-vertex type. I will also consider certain 9x9 and \n16x16 solutions and give new integrable models in all of these cases. As \na further application\, I will discuss all integrable deformations of\nR -matrices that appear in the lower-dimensional cases of the AdS/CFT\ncorre spondence.\n LOCATION:https://researchseminars.org/talk/LIJC/10/ END:VEVENT BEGIN:VEVENT SUMMARY:Sergei Lukyanov DTSTART:20200716T140000Z DTEND:20200716T160000Z DTSTAMP:20260422T230723Z UID:LIJC/11 DESCRIPTION:Title: De nsity matrix for the 2D black hole from an integrable spin chain\nby S ergei Lukyanov as part of London Integrability Journal Club\n\n\nAbstract\ nTwenty years ago Maldacena\, Ooguri and Son constructed a modular invaria nt partition function for the Euclidean black hole (cigar) NLSM. They als o proposed an expression for the corresponding density matrix.\nThis resul t played a key role in the formulation of the remarkable conjecture by Ikh lef\, Jacobsen and Saleur that the Euclidean black hole NLSM underlies the critical behaviour of a certain integrable spin chain.\nIn this talk we c ritically reexamine the above proposals.\n\nThe talk is based on the recen t (unpublished) joint work with\nV. Bazhanov and G. Kotousov.\n LOCATION:https://researchseminars.org/talk/LIJC/11/ END:VEVENT BEGIN:VEVENT SUMMARY:Davide Gaiotto (Perimeter) DTSTART:20200917T140000Z DTEND:20200917T160000Z DTSTAMP:20260422T230723Z UID:LIJC/12 DESCRIPTION:Title: 't Hooft operators and Q-functions\nby Davide Gaiotto (Perimeter) as par t of London Integrability Journal Club\n\n\nAbstract\nI will describe the role of 't Hooft operators in 4d Chern-Simons\ntheory and applications to integrability.\n LOCATION:https://researchseminars.org/talk/LIJC/12/ END:VEVENT BEGIN:VEVENT SUMMARY:Yifei He (IPhT\, Saclay) DTSTART:20200924T140000Z DTEND:20200924T160000Z DTSTAMP:20260422T230723Z UID:LIJC/13 DESCRIPTION:Title: Ge ometrical four-point functions in the 2d critical Q-state Potts model\ nby Yifei He (IPhT\, Saclay) as part of London Integrability Journal Club\ n\n\nAbstract\nAn important example among the 2d geometrical critical phen omena is the critical Q-state Potts model\, which describes the percolatio n in the limit Q-->1. In this talk I will consider the problem of determin ing the geometrical four-point functions (cluster connectivities) in this model. Connections with the minimal models are made which uncover remarkab le properties of the Potts amplitudes. Such properties allow to deduce the existence of "interchiral conformal blocks" which can be constructed usin g the degeneracy in the Potts spectrum. Using these\, I will then determin e the four-point functions through numerical bootstrap. In addition\, I wi ll also discuss the logarithmic nature of the Potts CFT and hints of a ful l analytic solution of the model.\n LOCATION:https://researchseminars.org/talk/LIJC/13/ END:VEVENT BEGIN:VEVENT SUMMARY:Pedro Vieira (Perimeter) DTSTART:20201001T140000Z DTEND:20201001T160000Z DTSTAMP:20260422T230723Z UID:LIJC/14 DESCRIPTION:Title: Mu lti-point Bootstrap and Integrability\nby Pedro Vieira (Perimeter) as part of London Integrability Journal Club\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/LIJC/14/ END:VEVENT BEGIN:VEVENT SUMMARY:Florian Loebbert (Humboldt U) DTSTART:20201008T141500Z DTEND:20201008T160000Z DTSTAMP:20260422T230723Z UID:LIJC/15 DESCRIPTION:Title: In tegrability for Feynman Integrals\nby Florian Loebbert (Humboldt U) as part of London Integrability Journal Club\n\n\nAbstract\nIn this talk I g ive an overview of the Yangian symmetry of Feynman integrals. After review ing the connection between AdS/CFT integrability and the Yangian symmetry of massless Feynman graphs\, I discuss the idea to bootstrap Feynman integ rals based on the Yangian constraints. Then I show that also in the massiv e case large classes of Feynman integrals are constrained by a Yangian ext ension of dual conformal symmetry. When translated to momentum space\, thi s leads to a novel massive generalization of ordinary conformal symmetry. Finally\, I argue that these features of massive Feynman integrals can be understood as the integrability of planar scattering amplitudes in a massi ve version of the so-called fishnet theory\, which is obtained as a double -scaling limit of N=4 super Yang-Mills theory on the Coulomb branch.\n LOCATION:https://researchseminars.org/talk/LIJC/15/ END:VEVENT BEGIN:VEVENT SUMMARY:Rouven Frassek (ENS) DTSTART:20201015T141500Z DTEND:20201015T160000Z DTSTAMP:20260422T230723Z UID:LIJC/16 DESCRIPTION:Title: QQ -system construction for so(2r) spin chains\nby Rouven Frassek (ENS) a s part of London Integrability Journal Club\n\n\nAbstract\nI will review t he QQ-system and oscillator construction of Q-operators for su(r+1) spin c hains and discuss its generalisation to so(2r) spin chains\n LOCATION:https://researchseminars.org/talk/LIJC/16/ END:VEVENT BEGIN:VEVENT SUMMARY:Lorenz Eberhardt (IAS) DTSTART:20201022T141500Z DTEND:20201022T160000Z DTSTAMP:20260422T230723Z UID:LIJC/17 DESCRIPTION:Title: An exact AdS/CFT correspondence\nby Lorenz Eberhardt (IAS) as part of Lo ndon Integrability Journal Club\n\n\nAbstract\nOne incarnation of the AdS/ CFT correspondence is the duality between the symmetric product orbifold o f T4 and superstrings on AdS3xS3xT4 with one unit of NS-NS flux. Compared to other instances of AdS/CFT\, this duality is much simpler and can in pr inciple be fully understood. I will give a broad overview of the inner wor kings of the duality from a worldsheet CFT point of view\, physical lesson s and connections to integrability.\n LOCATION:https://researchseminars.org/talk/LIJC/17/ END:VEVENT BEGIN:VEVENT SUMMARY:Roberto Tateo (INFN\, Torino) DTSTART:20201029T151500Z DTEND:20201029T170000Z DTSTAMP:20260422T230723Z UID:LIJC/18 DESCRIPTION:Title: Th e TTbar deformation and a promising 4D generalisation\nby Roberto Tate o (INFN\, Torino) as part of London Integrability Journal Club\n\n\nAbstra ct\nTwo-dimensional field theories deformed by Zamolodchikov's TTbar opera tor have recently attracted the attention of theoretical physicists due to the many important links with string theory and AdS/CFT. In this talk\, I will describe various classical and quantum aspects of this particular ir relevant perturbation\, including its geometrical interpretation at the cl assical level.\n I will also introduce a generalisation of this geometri cal framework to 4D field theories\, and discuss some of the interesting d ifferences with the 2D case.\n LOCATION:https://researchseminars.org/talk/LIJC/18/ END:VEVENT BEGIN:VEVENT SUMMARY:Tristan McLoughlin (Trinity Coll.\, Dublin) DTSTART:20201105T151500Z DTEND:20201105T170000Z DTSTAMP:20260422T230723Z UID:LIJC/19 DESCRIPTION:Title: No n-planar N=4 SYM: from integrability to quantum chaos\nby Tristan McLo ughlin (Trinity Coll.\, Dublin) as part of London Integrability Journal Cl ub\n\n\nAbstract\nIn this talk we will consider the spectrum of anomalous dimensions in N=4 super-Yang-Mills and related theories. We will first dis cuss the emergence of quantum chaos as one goes from infinite to finite N and how the perturbative spectrum is described by GOE random matrix theory . We will then describe how the integrability of the planar-limit can be u sed to rewrite the computation of the leading 1/N corrections to the one-l oop anomalous dimensions in terms of scalar products of off-shell Bethe st ates or\, alternatively\, hexagon-like functions.\n LOCATION:https://researchseminars.org/talk/LIJC/19/ END:VEVENT BEGIN:VEVENT SUMMARY:Nicolai Reshetikhin (UC\, Berkeley) DTSTART:20201112T151500Z DTEND:20201112T170000Z DTSTAMP:20260422T230723Z UID:LIJC/20 DESCRIPTION:Title: Su perintegrable systems on moduli spaces of flat connections\nby Nicolai Reshetikhin (UC\, Berkeley) as part of London Integrability Journal Club\ n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/LIJC/20/ END:VEVENT BEGIN:VEVENT SUMMARY:Jingxiang Wu (Perimeter) DTSTART:20201119T151500Z DTEND:20201119T170000Z DTSTAMP:20260422T230723Z UID:LIJC/21 DESCRIPTION:Title: In tegrable Kondo line defect\, 4D Chern Simons\, and ODE/IM correspondence\nby Jingxiang Wu (Perimeter) as part of London Integrability Journal Cl ub\n\n\nAbstract\nI will discuss the integrability and wall-crossing prope rties of Kondo line defects in rational conformal field theories. It provi des a large class of interesting defect RG flow starting from topological line defects. As a surprise\, I will discuss new examples of the ODE/IM co rrespondence and our attempts towards its physical origin using 4d Chern S imons theory. This work is part of a multi-pronged exploration of studying 4D Chern-Simons theory as an overarching structure for integrable systems .\n LOCATION:https://researchseminars.org/talk/LIJC/21/ END:VEVENT BEGIN:VEVENT SUMMARY:Jorge Russo (ICREA\, Barcelona) DTSTART:20201203T151500Z DTEND:20201203T170000Z DTSTAMP:20260422T230723Z UID:LIJC/22 DESCRIPTION:Title: Ph ases of unitary matrix models and lattice QCD in two dimensions\nby Jo rge Russo (ICREA\, Barcelona) as part of London Integrability Journal Club \n\n\nAbstract\nWe investigate the different large N phases of a deformed Gross-Witten-Wadia U(N) matrix model. The deformation\, which leads to a s olvable model\, corresponds to the addition of characteristic polynomial i nsertions and mimics the one-loop determinant of fermion matter. In one ve rsion of the model\, the GWW phase transition is smoothed out and it becom es a crossover. In another version\, the phase transition occurs along a c ritical line in the two-dimensional parameter space spanned by the 't~Hoof t coupling $\\lambda $ and the Veneziano parameter $\\tau $. A calculation of the $\\beta $ function shows the existence of an IR stable fixed point .\n LOCATION:https://researchseminars.org/talk/LIJC/22/ END:VEVENT BEGIN:VEVENT SUMMARY:Matthias Wilhelm (Niels Bohr Institutet) DTSTART:20201210T151500Z DTEND:20201210T170000Z DTSTAMP:20260422T230723Z UID:LIJC/23 DESCRIPTION:Title: An Operator Product Expansion for Form Factors\nby Matthias Wilhelm (Nie ls Bohr Institutet) as part of London Integrability Journal Club\n\n\nAbst ract\nIn this talk\, I discuss an operator product expansion for planar fo rm factors of local operators in N=4 SYM theory. In this expansion\, a for m factor is decomposed into a sequence of known pentagon transitions and a new universal object - the form factor transition. This transition is sub ject to a set of non-trivial bootstrap constraints\, which can be used to determine it at finite coupling. I demonstrate this for MHV form factors o f the chiral half of the stress tensor supermultiplet\, which in particula r contains the chiral Lagrangian and the 20'.\n LOCATION:https://researchseminars.org/talk/LIJC/23/ END:VEVENT BEGIN:VEVENT SUMMARY:LIJC Gong Show DTSTART:20201126T151500Z DTEND:20201126T170000Z DTSTAMP:20260422T230723Z UID:LIJC/24 DESCRIPTION:Title: LI JC Gong Show\nby LIJC Gong Show as part of London Integrability Journa l Club\n\n\nAbstract\n\\( \\)\n\nStefano Baiguera "Non-relativistic near-B PS corners of N=4 super Yang-Mills with SU(1\,1) symmetry"\n\nIlija Buric "From Integrable Gaudin Models to Multipoint Conformal Blocks"\n\nJulius J ulius "Baxter Equation for Boundary Integrability"\n\nRob Klabbers "How co ordinate Bethe ansatz works for Inozemtsev model"\n\nYuan Miao "On the Q-o perator and the spectrum of the XXZ model at root of unity"\n\nAnne Spieri ng "Integrability and Quantum Chaos in N=4 SYM from the Spectral Rigidity" \n\nAbstracts can be found on https://integrability-london.weebly.com/gong -show.html\n LOCATION:https://researchseminars.org/talk/LIJC/24/ END:VEVENT BEGIN:VEVENT SUMMARY:LIJC Gong Show DTSTART:20201217T151500Z DTEND:20201217T173500Z DTSTAMP:20260422T230723Z UID:LIJC/25 DESCRIPTION:Title: LI JC Gong Show\nby LIJC Gong Show as part of London Integrability Journa l Club\n\n\nAbstract\nSara Bonansea "Wilson loop correlators in defect N=4 SYM"\n\nAndrea Fontanella "Lie Algebra Expansion in Coset Sigma Models an d Non-relativistic String Theory"\n\nSuvajit Majumder "Protected states in AdS3xS3xT4 from integrability"\n\nGerben Oling "Non-relativistic strings and limits of AdS/CFT"\n\nChiara Paletta "Integrable open quantum systems" \n\nDavide Polvara "From tree-level perturbation theory to the S-matrix bo otstrap in two dimensions"\n\nAnton Pribytok "Deformed AdS Integrability a nd Free Fermion Condition"\n\nAbstracts can be found on https://integrabil ity-london.weebly.com/gong-show.html\n LOCATION:https://researchseminars.org/talk/LIJC/25/ END:VEVENT BEGIN:VEVENT SUMMARY:Paul Fendley (Oxford U.) DTSTART:20210114T151500Z DTEND:20210114T170000Z DTSTAMP:20260422T230723Z UID:LIJC/26 DESCRIPTION:Title: In tegrability and Braided Tensor Categories\nby Paul Fendley (Oxford U.) as part of London Integrability Journal Club\n\n\nAbstract\nMany integrab le critical classical statistical mechanical models and the corresponding quantum spin chains possess a fractional-spin conserved current. These cur rents have been constructed by utilising quantum-group algebras\, fermioni c and parafermionic operators\, and ideas from ``discrete holomorphicity'' . I define them generally and naturally using a braided tensor category\, a topological structure familiar from the study of knot invariants\, anyon s and conformal field theory. Such a current amounts to terminating a latt ice topological defect\, and I will touch on related work on such done wit h Aasen and Mong. I show how requiring a current be conserved yields simpl e constraints on the Boltzmann weights\, and that all of the many models k nown to satisfy these constraints are integrable. This procedure therefore gives a linear construction for ``Baxterising''\, i.e. building a solutio n of the Yang-Baxter equation out of topological data.\n LOCATION:https://researchseminars.org/talk/LIJC/26/ END:VEVENT BEGIN:VEVENT SUMMARY:Charlotte Kristjansen (Niels Bohr Institute) DTSTART:20210121T151500Z DTEND:20210121T170000Z DTSTAMP:20260422T230723Z UID:LIJC/27 DESCRIPTION:Title: Ov erlaps and Fermionic Dualities for Integrable Super Spin Chains\nby Ch arlotte Kristjansen (Niels Bohr Institute) as part of London Integrability Journal Club\n\n\nAbstract\nThe $\\mathfrak{psu}(2\,2|4)$ integrable supe r spin chain underlying the AdS/CFT correspondence has integrable boundary states which describe set-ups where $k$ D3-branes get dissolved in a prob e D5-brane. Overlaps between Bethe eigenstates and these boundary states e ncode the one-point functions of conformal operators and are expressed in terms of the superdeterminant of the Gaudin matrix that in turn depends on the Dynkin diagram of the symmetry algebra. The different possible Dynkin diagrams of super Lie algebras are related via fermionic dualities and we determine how overlap formulae transform under these dualities. As an app lication we show how to consistently move between overlap formulae obtaine d for $k=1$ from different Dynkin diagrams.\n LOCATION:https://researchseminars.org/talk/LIJC/27/ END:VEVENT BEGIN:VEVENT SUMMARY:Gustavo Joaquin Turiaci (UC\, Santa Barbara) DTSTART:20210128T151500Z DTEND:20210128T170000Z DTSTAMP:20260422T230723Z UID:LIJC/28 DESCRIPTION:Title: 2D dilaton-gravity\, matrix models\, and the minimal string\nby Gustavo Joaquin Turiaci (UC\, Santa Barbara) as part of London Integrability Journ al Club\n\n\nAbstract\nIn the first part of this talk I will review the re cent realization that a large class of two-dimensional theories of dilaton -gravity in asymptotically AdS space are holographically dual to a random matrix model. In this description the matrix represents a random boundary Hamiltonian\, and its probability distribution depends on the dilaton pote ntial in a specific way. In the second part of the talk I will explain the relation between two-dimensional dilaton-gravity and the minimal string t heory.\n LOCATION:https://researchseminars.org/talk/LIJC/28/ END:VEVENT BEGIN:VEVENT SUMMARY:Junya Yagi (Perimeter) DTSTART:20210204T151500Z DTEND:20210204T170000Z DTSTAMP:20260422T230723Z UID:LIJC/29 DESCRIPTION:Title: Wi lson-'t Hooft lines as transfer matrices\nby Junya Yagi (Perimeter) as part of London Integrability Journal Club\n\n\nAbstract\nSupersymmetric g auge theories in four dimensions have various interrelated connections to quantum integrable systems. I will present a new correspondence which iden tifies Wilson-'t Hooft lines in N=2 circular quiver theories with transfer matrices of trigonometric systems. I will explain how this correspondence is related to Costello's 4d Chern-Simons theory and other similar corresp ondences. This is based on my joint work with Kazunobu Maruyoshi and Toshi hiro Ota.\n LOCATION:https://researchseminars.org/talk/LIJC/29/ END:VEVENT BEGIN:VEVENT SUMMARY:Oleksandr Gamayun (Amsterdam U.) DTSTART:20210211T151500Z DTEND:20210211T170000Z DTSTAMP:20260422T230723Z UID:LIJC/30 DESCRIPTION:Title: Mo deling finite-entropy states with free fermions\nby Oleksandr Gamayun (Amsterdam U.) as part of London Integrability Journal Club\n\n\nAbstract\ nThe behavior of dynamical correlation functions in one-dimensional quantu m systems at zero temperature is now very well understood in terms of line ar and non-linear Luttinger models. The "microscopic" justification of the se models consists in exactly accounting for the soft-mode excitations aro und the vacuum state and at most a few high-energy excitations. At finite temperature\, or more generically for finite entropy states\, this direct approach is not strictly applicable due to the different structure of soft excitations. To address these issues we study the asymptotic behavior of correlation functions in one-dimensional free fermion models. On the one h and\, we obtain exact answers in terms of Fredholm determinants. On the ot her hand\, based on "microscopic" numerical resummations\, we develop a ph enomenological approach that provides results depending only on the state- dependent dressing of the scattering phase. Our main example will be the s ine-kernel and correlation functions in XY model.\n LOCATION:https://researchseminars.org/talk/LIJC/30/ END:VEVENT BEGIN:VEVENT SUMMARY:Volker Schomerus (DESY) DTSTART:20210218T151500Z DTEND:20210218T170000Z DTSTAMP:20260422T230723Z UID:LIJC/31 DESCRIPTION:Title: Co nformal Fourier Analysis and Gaudin Integrability\nby Volker Schomerus (DESY) as part of London Integrability Journal Club\n\n\nAbstract\nConfor mal partial wave expansion provide Fourier-like decompositions of correlat ion functions in Conformal Field Theory. Despite their fundamental importa nce\, conformal partial waves remain poorly understood\, at least beyond t he case of four local fields. In the last few years\, a deep relation with integrable quantum mechanical models has emerged. It offers a wealth of p owerful new algebraic methods to study and construct conformal partial wav es e.g. for general supermultiplets\, non-local (line-\, surface-) operato rs and multi-point correlation functions. In my talk I will use ideas from harmonic analysis of the conformal group to embed conformal partial waves into the framework of Gaudin integrable models and then discuss several c oncrete ramifications as trigonometric and elliptic Calogero-Sutherland mo dels. The latter are relevant for multi-point blocks of scalar fields.\n LOCATION:https://researchseminars.org/talk/LIJC/31/ END:VEVENT BEGIN:VEVENT SUMMARY:Benoit Vicedo DTSTART:20210225T151500Z DTEND:20210225T170000Z DTSTAMP:20260422T230723Z UID:LIJC/32 DESCRIPTION:Title: In tegrable E-models\, 4d Chern-Simons theory and affine Gaudin models\nb y Benoit Vicedo as part of London Integrability Journal Club\n\n\nAbstract \nTwo-dimensional integrable field theories are characterised by the exist ence of infinitely many integrals of motion. Recently\, two unifying frame works for describing such theories have emerged\, based on four-dimensiona l Chern-Simons theory in the presence of surface defects and on Gaudin mod els associated with affine Kac-Moody algebras. I will explain how these fo rmalisms can be used to construct infinite families of two-dimensional int egrable field theories. The latter can all naturally be formulated as so-c alled E-models\, a framework for describing Poisson-Lie T-duality in sigma -models. The talk will be based on the joint work [arXiv:2008.01829] with M. Benini and A. Schenkel and [2011.13809] with S. Lacroix.\n LOCATION:https://researchseminars.org/talk/LIJC/32/ END:VEVENT BEGIN:VEVENT SUMMARY:Frank Coronado (McGill U.) DTSTART:20210304T151500Z DTEND:20210304T170000Z DTSTAMP:20260422T230723Z UID:LIJC/33 DESCRIPTION:Title: Te n dimensional hidden symmetry of N=4 SYM\nby Frank Coronado (McGill U. ) as part of London Integrability Journal Club\n\n\nAbstract\nI will prese nt a generating function for the loop-integrands of all four-point functio ns of protected single-trace operators in N=4 super Yang-Mills. This funct ion enjoys a ten-dimensional symmetry that combines spacetime and the inte rnal R-charge symmetries. By considering a 10D light-like limit I will est ablish a relationship between the simplest four-point correlators (octagon s) and four-particle amplitudes.\n LOCATION:https://researchseminars.org/talk/LIJC/33/ END:VEVENT BEGIN:VEVENT SUMMARY:Nikita Nekrasov (Stony Brook U.\, New York\, SCGP) DTSTART:20210311T151500Z DTEND:20210311T170000Z DTSTAMP:20260422T230723Z UID:LIJC/34 DESCRIPTION:Title: Le fschetz thimbles in sigma models\nby Nikita Nekrasov (Stony Brook U.\, New York\, SCGP) as part of London Integrability Journal Club\n\n\nAbstra ct\nTwo dimensional sigma models describe (harmonic) maps of Riemann surfa ces to Riemannian manifolds. I will present the motivations to study the c omplexification of this problem. I will present the novel approach\, devel oped in my work with Igor Krichever\, allowing to construct essentially al l twisted complexified harmonic maps of two-torus to spheres and projectiv e spaces.\n LOCATION:https://researchseminars.org/talk/LIJC/34/ END:VEVENT BEGIN:VEVENT SUMMARY:Takato Yoshimura (Tokyo Inst. Tech.) DTSTART:20210318T110000Z DTEND:20210318T130000Z DTSTAMP:20260422T230723Z UID:LIJC/35 DESCRIPTION:Title: TT bar-deformed conformal field theories out of equilibrium\nby Takato Yo shimura (Tokyo Inst. Tech.) as part of London Integrability Journal Club\n \n\nAbstract\nIn this talk I will discuss the universal properties of tran sport phenomena in TTbar-deformed conformal field theories. TTbar-deformed CFTs are exactly solvable and admit a number of approaches\, each of whic h is seemingly unrelated. Amongst them\, for our purpose\, which is to stu dy transport phenomena in TTbar-deformed CFTs\, we make use of the followi ng: integrability and holography. I will apply these two approaches to stu dy non-equilibrium steady states and Drude weights\, finding perfect agree ment. I will also discuss a curious connection between TTbar-deformed CFTs and an integrable cellular automaton model called the Rule 54 chain.\n LOCATION:https://researchseminars.org/talk/LIJC/35/ END:VEVENT BEGIN:VEVENT SUMMARY:Igor Klebanov (Princeton U.) DTSTART:20210325T151500Z DTEND:20210325T170000Z DTSTAMP:20260422T230723Z UID:LIJC/36 DESCRIPTION:Title: Co nfining or Not?\nby Igor Klebanov (Princeton U.) as part of London Int egrability Journal Club\n\n\nAbstract\nThe problem of Color Confinement in Yang-Mills theory is one of the deepest problems in theoretical physics. There is convincing numerical evidence from Lattice Gauge Theory\, yet the proof of Confinement in Asymptotically Free theories has not been found. I will briefly introduce the Confinement problem and review some results o n large N theories using the gauge/gravity duality. I will then discuss tw o-dimensional SU(N) theory coupled to an adjoint Majorana fermion. I will show that\, when the adjoint mass is sent to zero\, the spectrum retains a mass gap but the confinement disappears. Using the Discretized Light-Cone Quantization\, I will discuss the spectrum of color singlet states and ex hibit certain threshold states. Similar threshold states are also present in a model with a massless adjoint and a massive fundamental fermion. They provide new evidence for the lack of confinement. When the adjoint mass i s turned on\, the theory becomes confining\, and the spectrum of bound sta tes becomes discrete.\n LOCATION:https://researchseminars.org/talk/LIJC/36/ END:VEVENT BEGIN:VEVENT SUMMARY:Sylvain Lacroix DTSTART:20210401T141500Z DTEND:20210401T160000Z DTSTAMP:20260422T230723Z UID:LIJC/37 DESCRIPTION:Title: Af fine Gaudin models and integrable sigma-models\nby Sylvain Lacroix as part of London Integrability Journal Club\n\n\nAbstract\nIn this talk\, I will discuss how the formalism of affine Gaudin models can be used to cons truct new integrable sigma-models. I will start by reviewing the construct ion of affine Gaudin models and their interpretation as integrable two-dim ensional field theories. I will then explain how well-chosen realisations of these models give integrable coupled sigma model on an arbitrary number of copies of a Lie group G^N as well as integrable coset models on the qu otient of G^N by a diagonal subgroup. In particular\, I will discuss appli cation of the latter construction to T^11 manifolds.\n LOCATION:https://researchseminars.org/talk/LIJC/37/ END:VEVENT BEGIN:VEVENT SUMMARY:Vladimir Korepin (SUNY\, Stony Brook) DTSTART:20210422T141500Z DTEND:20210422T160000Z DTSTAMP:20260422T230723Z UID:LIJC/38 DESCRIPTION:Title: La ttice nonlinear Schroedinger equation: history and open problems\nby V ladimir Korepin (SUNY\, Stony Brook) as part of London Integrability Journ al Club\n\n\nAbstract\nThe model has many names: Lieb-Liniger\, Bose gas w ith delta interaction and nonlinear Schoedinger. A limiting case is called Tonks-Girardeau. It is solvable by algebraic Bethe ansatz. We shall use n otations of quantum inverse scattering method. Applications will be mentio ned.\n LOCATION:https://researchseminars.org/talk/LIJC/38/ END:VEVENT BEGIN:VEVENT SUMMARY:Benjamin Basso DTSTART:20210429T141500Z DTEND:20210429T160000Z DTSTAMP:20260422T230723Z UID:LIJC/39 DESCRIPTION:Title: Sc attering Amplitudes Near the Origins: Localization and Globalization\n by Benjamin Basso as part of London Integrability Journal Club\n\n\nAbstra ct\nI will talk about the behaviour of gluon scattering amplitudes in plan ar N=4 SYM near kinematical corners coined Origins where maximally-helicit y-violating amplitudes are expected to be exactly Gaussian in the logs of the cross ratios and exactly predictable. In part 1\, I will recall how mu ch is known about this behaviour for the 6-gluon amplitude and interpret t he result as a sort of quantum area convoluting the minimal surface TBA da ta with an effective coupling constant\, known as the tilted cusp anomalou s dimension. In part 2\, I will present a generalization to any number of gluons and explore (some bit of) the emerging parterre of Origins. If time permits\, I will discuss applications to scattering amplitudes in the nul l limit where all two-particle Mandelstam vanish simultaneously. The talk is based on a work in progress with Lance Dixon\, Yu-Ting Liu and Georgios Papathanasiou.\n LOCATION:https://researchseminars.org/talk/LIJC/39/ END:VEVENT BEGIN:VEVENT SUMMARY:Yunfeng Jiang (Southeast U.\, Nanjing) DTSTART:20210513T141500Z DTEND:20210513T160000Z DTSTAMP:20260422T230723Z UID:LIJC/41 DESCRIPTION:Title: OP E coefficients in ABJM theory with giants\nby Yunfeng Jiang (Southeast U.\, Nanjing) as part of London Integrability Journal Club\n\n\nAbstract\ nIn this talk\, I will discuss a family of three-point functions in ABJM t heory\, both at weak and strong coupling. This family of three-point funct ions involve two BPS sub-determinant operators called giant gravitons and one single trace operator\, which can be BPS or non-BPS. In the first part of the talk\, I will explain how to compute this type of three-point func tion at weak coupling using a large N effective field theory. The structur e constant is given by the overlap of an integrable matrix product state a nd a Bethe state. In the second part\, I will first clarify the prescripti on of computation at strong coupling. I will show that it is important to perform an average over the moduli space and also take into account the co ntributions from wave functions. The prescription is tested in N=4 SYM the ory and then applied to ABJM theory.\n LOCATION:https://researchseminars.org/talk/LIJC/41/ END:VEVENT BEGIN:VEVENT SUMMARY:Congkao Wen (QMUL) DTSTART:20210520T141500Z DTEND:20210520T160000Z DTSTAMP:20260422T230723Z UID:LIJC/42 DESCRIPTION:Title: In tegrated four-point correlators in N=4 super Yang-Mills\nby Congkao We n (QMUL) as part of London Integrability Journal Club\n\n\nAbstract\nWe wi ll study the correlation function of four superconformal primaries in N=4 super Yang-Mills (SYM) with SU(N) gauge group. Recently\, very powerful me thods have been developed to compute this correlator at finite coupling ba sed on a new concept of integrated correlators\, which are defined by inte grating the correlator over spacetime coordinates with suitable integratio n measures. The integrated correlators can be computed using supersymmetri c localisation. We will mostly focus on one of the integrated correlators. An exact expression was found for this integrated correlator for arbitrar y values of coupling and N. The integrated correlator can be expressed as a two-dimensional lattice sum\, which manifests the SL(2\, Z) modular inva riance of N=4 SYM. Furthermore\, the result obeys an elegant Laplace-diffe rence equation that relates the correlator of SU(N) theory with those of S U(N-1) and SU(N+1) theories. In perturbation\, the formula is checked to b e consistent with known results from more standard methods. Finally\, one can reconstruct the unintegrated correlator with finite coupling for first few orders in large-N expansion\, the results are shown to agree with kno wn type IIB superstring amplitudes due to AdS/CFT duality. This talk will be mainly based on https://arxiv.org/abs/2102.09537 (a short version can b e found at https://arxiv.org/abs/2102.08305).\n LOCATION:https://researchseminars.org/talk/LIJC/42/ END:VEVENT BEGIN:VEVENT SUMMARY:Balazs Pozsgay (Eotvos U.) DTSTART:20210506T141500Z DTEND:20210506T160000Z DTSTAMP:20260422T230723Z UID:LIJC/43 DESCRIPTION:Title: Cu rrent operators in integrable models (a review)\nby Balazs Pozsgay (Eo tvos U.) as part of London Integrability Journal Club\n\n\nAbstract\nCurre nt operators describe the flow of the conserved charges in integrable mode ls. Whereas lots of information was known about the charges\, surprisingly the current operators remained unexplored for a very long time. I review recent results in this topic\, which include an exact finite volume formul a for the mean values of the current operators\, their embedding into the Quantum Inverse Scattering Approach (Algebraic Bethe Ansatz)\, and connect ions with long range deformations and TTbar deformations.\n LOCATION:https://researchseminars.org/talk/LIJC/43/ END:VEVENT BEGIN:VEVENT SUMMARY:Gong Show DTSTART:20210527T141500Z DTEND:20210527T160000Z DTSTAMP:20260422T230723Z UID:LIJC/44 DESCRIPTION:Title: LI JC Gong Show\nby Gong Show as part of London Integrability Journal Clu b\n\n\nAbstract\nSchedule:\n\n15.15-15.30 \, Nat Levine\, "Embedding integ rable sigma models in string theory"\n\n15.30-15.45\, Juan Miguel Nieto G arcia\, "Three-parameter deformation of R×S3 in the Landau-Lifshitz limit "\n\n15.45-16.00\, Tomas Reis\, "Renormalons from Resurgence"\n\n16.00-16. 15\, Coffe-break\n\n16.15-16.30\, Gabriel Bliard\, "Mellin amplitudes for 1D CFT" \n\n16.30-16.45\, Fabrizio Del Monte\, "BPS quivers of five-dimens ional SCFTs\, Topological Strings and q-Painlevé equations"\n\n16.45-17.0 0\, Leonardo Santilli\, "TTbar deformation of q-Yang-Mills theory"\n LOCATION:https://researchseminars.org/talk/LIJC/44/ END:VEVENT BEGIN:VEVENT SUMMARY:Ofer Aharony (Weizmann Inst.) DTSTART:20210603T141500Z DTEND:20210603T160000Z DTSTAMP:20260422T230723Z UID:LIJC/45 DESCRIPTION:Title: A gravity interpretation for the Bethe ansatz expansion of the N=4 SYM super conformal index\nby Ofer Aharony (Weizmann Inst.) as part of London In tegrability Journal Club\n\n\nAbstract\nThis (blackboard) talk is based on 2104.13932 and on work in progress with Francesco Benini\, Ohad Mamroud a nd Paolo Milan. I will begin by briefly reviewing the superconformal index of the d=4 N=4 SU(N) supersymmetric Yang-Mills theory\, how it is related (in the large N limit) to counting black hole microstates\, and how it ca n be computed. I will then review a specific way to compute the index call ed the Bethe ansatz expansion\, and describe the known solutions to the Be the ansatz equations\, and what they contribute to the index in the large N limit\, including both perturbative and non-perturbative terms in 1/N. T he index is related to the partition function of N=4 SYM on S^3xS^1\, and in the large N limit this should be related by the AdS/CFT correspondence to a sum over Euclidean gravity solutions with appropriate asymptotic beha vior. I will show that each known Bethe ansatz contribution arises from a specific supersymmetric (complex) black hole solution\, which reproduces b oth its perturbative and its non-perturbative behavior (the latter comes f rom wrapped Euclidean D3-branes). A priori there are many more gravitation al solutions than Bethe ansatz contributions\, but we show that by conside ring the non-perturbative effects\, the extra solutions are ruled out\, le ading to a precise match between the solutions on both sides.\n LOCATION:https://researchseminars.org/talk/LIJC/45/ END:VEVENT BEGIN:VEVENT SUMMARY:Vladimir Kazakov (ENS Paris) DTSTART:20210610T141500Z DTEND:20210610T160000Z DTSTAMP:20260422T230723Z UID:LIJC/46 DESCRIPTION:Title: Du ally weighted graphs and 2d quantum gravity\nby Vladimir Kazakov (ENS Paris) as part of London Integrability Journal Club\n\n\nAbstract\nDually weighted graphs (DWG) are planar Feynman graphs bearing two sets of coup lings: one set of usual couplings $t_n$ attached to the vertices of valen ce $n$\, and another set of dual couplings $t_n^*$ attached to the faces (dual vertices) of valence $n$. Such couplings allow a deep control on possible shapes of planar graphs. For example\, if one turns on only th e couplings $t_4$ and $t_4^*$ the graph takes a "fishnet form" of a regu lar square lattice. The problem of counting of such graphs can be formulat ed as a modified hermitian one matrix model with an extra constant matrix. The partition function can be then represented in terms of the "character expansion" over Young tableaux\, solvable by the saddle point approximat ion. I will review old results on DWG from my papers with M.Staudacher and Th.Wynter\, including the techniques of computing Schur characters of a large Young tableau and deriving the elliptic algebraic curve for coun ting of planar quadrangulations. Then I will present new results from our ongoing work with F.Levkovich-Maslyuk where we count the disc quadrangu lations with large\, macroscopic area and boundary. This allows to extract interesting continuous limit of fluctuating 2d geometry\, interpolating between the "almost" flat disc with a few dynamical conical defects and the disc partition function for pure 2d quantum gravity\, generalizing old results for the spherical topology.\n LOCATION:https://researchseminars.org/talk/LIJC/46/ END:VEVENT BEGIN:VEVENT SUMMARY:LIJC Gong Show DTSTART:20210617T134500Z DTEND:20210617T150000Z DTSTAMP:20260422T230723Z UID:LIJC/47 DESCRIPTION:by LIJC Gong Show as part of London Integrability Journal Club \n\n\nAbstract\nSchedule:\n\n14.45 - 15.00\, Ilija Buric\, "Defect conform al blocks from the Iwasawa decomposition"\n\n15.00 - 15.15\, Daniele Grego ri\, "Integrability and cycles of deformed N=2 gauge theory"\n\n15.15 - 15 .30\, Luigi Guerrini\, "A duality for the latitude Wilson loop in ABJM"\n\ n15.30 - 15.45\, Enrico Olivucci\, "Hexagons in Fishnet theories: direct d erivation"\n LOCATION:https://researchseminars.org/talk/LIJC/47/ END:VEVENT BEGIN:VEVENT SUMMARY:Zohar Komargodski (Stony Brook U.\, New York\, SCGP) DTSTART:20211007T144500Z DTEND:20211007T163000Z DTSTAMP:20260422T230723Z UID:LIJC/48 DESCRIPTION:Title: Re normalization Group Flows on Line Defects\nby Zohar Komargodski (Stony Brook U.\, New York\, SCGP) as part of London Integrability Journal Club\ n\n\nAbstract\nWe will review the subject of line defects in d-dimensional Conformal Field Theories (CFTs). We discuss an exact formula governing th e renormalization group flow on line defects and consider some examples in volving line defects in 2\,3\, and 4 space-time dimensions.\n LOCATION:https://researchseminars.org/talk/LIJC/48/ END:VEVENT BEGIN:VEVENT SUMMARY:Elli Pomoni (DESY) DTSTART:20211014T144500Z DTEND:20211014T163000Z DTSTAMP:20260422T230723Z UID:LIJC/49 DESCRIPTION:Title: Dy namical spin chains in 4D N = 2 SCFTs\nby Elli Pomoni (DESY) as part o f London Integrability Journal Club\n\n\nAbstract\nIn this talk we will re visit the study of spin chains capturing the spectral problem of 4d N = 2 SCFTs in the planar limit. At one loop and in the quantum plane limit\, we will discover a quasi-Hopf symmetry algebra\, defined by the R-matrix rea d off from the superpotential. This implies that when orbifolding the N = 4 symmetry algebra down to the N = 2 one and then marginaly deforming\, th e broken generators are not lost\, but get upgraded to quantum generators. We will also demonstrate that these chains are dynamical\, in the sense t hat their Hamiltonian depends on a parameter which is dynamically determin ed along the chain. At one loop we will show how to map the holomorphic SU (3) scalar sector to a dynamical 15-vertex model\, which corresponds to an RSOS model\, whose adjacency graph can be read off from the gauge theory quiver/brane tiling. One scalar SU(2) sub-sector is described by an altern ating nearest-neighbour Hamiltonian\, while another choice of SU(2) sub-se ctor leads to a dynamical dilute Temperley-Lieb model. These sectors have a common vacuum state\, around which the magnon dispersion relations are n aturally uniformised by elliptic functions. For the example of the ℤ_{2} quiver theory we study these dynamical chains by solving the one- and two -magnon problems with the coordinate Bethe ansatz approach.\n LOCATION:https://researchseminars.org/talk/LIJC/49/ END:VEVENT BEGIN:VEVENT SUMMARY:Zechuan Zheng (ENS Paris) DTSTART:20211021T144500Z DTEND:20211021T163000Z DTSTAMP:20260422T230723Z UID:LIJC/50 DESCRIPTION:Title: Ma trix bootstrap revisited\nby Zechuan Zheng (ENS Paris) as part of Lond on Integrability Journal Club\n\n\nAbstract\nMatrix bootstrap is a new met hod for the numerical study of (multi)-matrix models in the planar limit\, using loop equations for moments of distribution (Ward identities and fac torization of traces at infinite N). The lack of information associated wi th the use of only a finite number of lower moments is supplemented by the conditions of positivity of the correlation matrix. The numerical solutio n of loop equations and these conditions leads to inequalities for the low est moments\, which rapidly converge to exact values ​​with an increas e in the number of used moments. In our work https://arxiv.org/pdf/2108.04 830.pdf\, the method was tested on the example of the standard one-matrix model\, as well as on the case of an “unsolvable” 2-matrix model with the interaction $tr[A\, B]^2$ and with quartic potentials. We propose a si gnificant improvement of original H.Lin’s proposal for matrix bootstrap by introducing the relaxation procedure: we replace the non-convex\, non-l inear loop equations by convex inequalities. The results look quite convin cing and matrix bootstrap seems to be an interesting alternative to the Mo nte Carlo method. For example\, for $\\langle tr A^2 \\rangle$\, the preci sion reaches 6 digits (with modest computer resources). I will discuss the prospects for applying the method in other\, physically interesting syste ms.\n LOCATION:https://researchseminars.org/talk/LIJC/50/ END:VEVENT BEGIN:VEVENT SUMMARY:Simeon Hellerman (Tokyo U.\, IPMU) DTSTART:20211104T100000Z DTEND:20211104T120000Z DTSTAMP:20260422T230723Z UID:LIJC/51 DESCRIPTION:Title: Pr ecision Correlators at Large R-Charge\nby Simeon Hellerman (Tokyo U.\, IPMU) as part of London Integrability Journal Club\n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/LIJC/51/ END:VEVENT BEGIN:VEVENT SUMMARY:Jake Stedman DTSTART:20211111T154500Z DTEND:20211111T173000Z DTSTAMP:20260422T230723Z UID:LIJC/52 DESCRIPTION:Title: Ga uged sigma models from four-dimensional Chern-Simons\nby Jake Stedman as part of London Integrability Journal Club\n\n\nAbstract\nSeveral years ago\, a new gauge theory called four-dimensional Chern-Simons was introduc ed by Costello in an attempt to explain the integrability of various two-d imensional models using techniques in gauge theory. My work focuses on the use of four-dimensional Chern-Simons to explain the integrability of two- dimensional sigma models. I will begin by reviewing the construction of th e Wess-Zumino-Witten (WZW) model as the boundary theory of three-dimension al Chern-Simons theory as was introduced by Moore and Seiberg. This will a llow me to introduce the analogous construction of Costello and Yamazaki\, in which two-dimensional sigma models appear as theories on defects in fo ur-dimensional Chern-Simons. This naturally leads to a discussion of my wo rk in which I construct a large class of gauged sigma models by coupling t ogether two four-dimensional Chern-Simons theories. I will argue that the structure of four-dimensional Chern-Simons suggests that these models are integrable and finish by constructing the gauged WZW model and conformal T oda theories. This talk is based on: https://arxiv.org/abs/2109.08101.\n LOCATION:https://researchseminars.org/talk/LIJC/52/ END:VEVENT BEGIN:VEVENT SUMMARY:Mykola Dedushenko (SUNY\, Stony Brook) DTSTART:20211028T144500Z DTEND:20211028T163000Z DTSTAMP:20260422T230723Z UID:LIJC/53 DESCRIPTION:Title: Qu antum algebras and SUSY interfaces in Bethe/gauge correspondence\nby M ykola Dedushenko (SUNY\, Stony Brook) as part of London Integrability Jour nal Club\n\n\nAbstract\nI will describe my work with N.Nekrasov on supersy mmetric interfaces in gauge theories in the context of the Bethe/gauge cor respondence. These interfaces\, viewed as operators on the Hilbert space\, give linear maps between spaces of SUSY vacua\, understood mathematically as generalized cohomology theories of the Higgs branch. A natural class o f interfaces are SUSY Janus interfaces for masses\, with the corresponding cohomological maps being either the stable envelopes or the chamber R-mat rices (both due to Maulik-Okounkov and Aganagic-Okounkov). Thus\, such int erfaces (and their collisions) can be used to define actions of the spectr um generating algebras (such as Yangians) on the "gauge" side of the Bethe /gauge correspondence\, i.e.\, in QFT. Further applications and possible g eneralizations will be mentioned as well.\n LOCATION:https://researchseminars.org/talk/LIJC/53/ END:VEVENT BEGIN:VEVENT SUMMARY:GONG SHOW DTSTART:20211125T144500Z DTEND:20211125T163000Z DTSTAMP:20260422T230723Z UID:LIJC/54 DESCRIPTION:Title: LI JC Gong Show\nby GONG SHOW as part of London Integrability Journal Clu b\n\n\nAbstract\nSchedule :\n\n14:45 - 15:00 Meer Ashwinkumar\n\n15 :00 - 15:15 Levente Pristyák\n\n15:15 - 15:30 Xinyu Zhang\ n\n15:30 - 15:45 Coffee break/Discussion\n​\n15:45 - 16:00 Carlos Bercini\n\n16:00 - 16:15 Aleix Gimenez-Grau\n\n16:15 - 16:3 0 Himanshu Khanchandani\n\n16:30 - 16:45 Discussion\n \n\nMe er Ashwinkumar\, Kavli Inst. Tokyo\, "Three-dimensional WZW model and the R-matrix of the Yangian"\n\nCarlos Bercini\, ICTP-SAIFR\, "The Wilson Loop - Large Spin OPE Dictionary"\n\nAleix Gimenez-Grau\, DESY\, "Bootstrappin g holographic defect correlators"\n\nHimanshu Khanchandani\, Princeton Uni v.\, "CFT in AdS and Gross-Neveu BCFT"\n\nLevente Pristyák\, Budapest Uni v.\, "Current operators in the XYZ model"\n\nXinyu Zhang\, DESY\, "Hidden symmetry in 4d N=2 quiver gauge theory"\n\nAbstracts can be found in the G ong Show section of the LIJC website.\n LOCATION:https://researchseminars.org/talk/LIJC/54/ END:VEVENT BEGIN:VEVENT SUMMARY:Roland Bittleston (Perimeter Inst. Theor. Phys.) DTSTART:20211209T154500Z DTEND:20211209T173000Z DTSTAMP:20260422T230723Z UID:LIJC/55 DESCRIPTION:Title: Bo sonic string from Beltrami Chern-Simons\nby Roland Bittleston (Perimet er Inst. Theor. Phys.) as part of London Integrability Journal Club\n\n\nA bstract\nIt is well understood how the 2d free scalar CFT emerges from 3d Chern-Simons theory with chiral boundary conditions. Adapting a recent pro posal of Costello and Stefański\, I will show how bosonic string theory c an be obtained from this description by coupling to a dynamical Beltrami d ifferential in the 3d theory. In particular\, I will show how this Beltram i differential restores worldsheet diffeomorphism and Weyl invariance in t he 2d theory\, and recover the Polyakov action explicitly. By rewriting th e theory in the BV formalism\, I will show how the bc ghost system arises from the 3d perspective. Finally\, if there is sufficient time\, I’ll pr ovide the 3d realization of vertex operators. This talk is based on work i n progress with Kevin Costello and Bogdan Stefański.\n LOCATION:https://researchseminars.org/talk/LIJC/55/ END:VEVENT BEGIN:VEVENT SUMMARY:Benjamin Doyon DTSTART:20211118T154500Z DTEND:20211118T173000Z DTSTAMP:20260422T230723Z UID:LIJC/57 DESCRIPTION:Title: Co rrelation functions of twist fields from hydrodynamics\nby Benjamin Do yon as part of London Integrability Journal Club\n\n\nAbstract\nThe Euler- scale power-law asymptotics of space-time correlation functions in many-bo dy systems\, quantum and classical\, can be obtained by projecting the obs ervables onto the hydrodynamic modes admitted by the model and state. This is the Boltzmann-Gibbs principle\; it works for integrable and non-integr able models alike. However\, certain observables\, such as some order para meters in thermal of generalised Gibbs ensembles\, do not couple to any hy drodynamic mode: the Boltzmann-Gibbs principle gives zero. I will explain how hydrodynamics can still give the leading exponential decay of order pa rameter correlation functions. With the examples of the quantum XX chain a nd the sine-Gordon model\, I will explain how large deviations of the spin and U(1) current fluctuations are related to such exponential decay. Exac t predictions are given by the ballistic fluctuation theory based on gener alised hydrodynamics. In the XX model\, this is in agreement with results obtained previously by a more involved Fredholm determinant analysis and o ther techniques\, and even gives a new formula for a parameter regime not hitherto studied. In the sine-Gordon model\, these are new results\, inacc essible by other techniques. Works in collaboration with Giuseppe Del Vecc hio Del Vecchio\, and Márton Kormos.\n LOCATION:https://researchseminars.org/talk/LIJC/57/ END:VEVENT BEGIN:VEVENT SUMMARY:Jakub Vošmera (ETH Zurich) DTSTART:20211202T144500Z DTEND:20211202T163000Z DTSTAMP:20260422T230723Z UID:LIJC/58 DESCRIPTION:Title: D- branes in AdS3xS3xT4 at k=1 and their holographic duals\nby Jakub Voš mera (ETH Zurich) as part of London Integrability Journal Club\n\n\nAbstra ct\nFollowing the recent work of Eberhardt\, Gaberdiel and Gopakumar\, exa ct comparison between various quantities living on the two sides of the Ad S/CFT duality has become a possibility. The goal of this talk will be to e xtend the existing holographic dictionary to include some non-perturbative vacua on both sides. I will start by reviewing the original\, purely clos ed-string setup\, giving arguments that string theory on ${\\rm AdS}_3\\ti mes {\\rm S}^3 \\times \\mathbb{T}^4$ with minimal $k=1$ NS-NS flux is exa ctly dual to the symmetric-product orbifold CFT with the $\\mathbb{T}^4$ a s the seed. I will then construct various D-branes of this string theory a nd calculate their associated cylinder amplitudes. We will observe that th ese amplitudes match with the cylinder correlators of certain boundary sta tes of the dual CFT\, thus suggesting a direct correspondence between thes e boundary conditions. I will also show that the disk amplitudes of these D-branes localise to those points in the worldsheet moduli space where the worldsheet disk holomorphically covers the spacetime disk. This talk is b ased on https://arxiv.org/abs/2110.05509.\n LOCATION:https://researchseminars.org/talk/LIJC/58/ END:VEVENT BEGIN:VEVENT SUMMARY:Arkady Tseytlin (Imperial Coll.\, London) DTSTART:20220127T144500Z DTEND:20220127T163000Z DTSTAMP:20260422T230723Z UID:LIJC/59 DESCRIPTION:Title: Wi lson loop in general representation and RG flow in 1d defect QFT\nby A rkady Tseytlin (Imperial Coll.\, London) as part of London Integrability J ournal Club\n\n\nAbstract\nThe generalized Wilson loop operator interpolat ing between the supersymmetric and the ordinary Wilson loop in N=4 SYM the ory provides an interesting example of renormalization group flow on a lin e defect: the scalar coupling parameter \\zeta has a non-trivial beta func tion and may be viewed as a running coupling constant in a 1d defect QFT.\ nWe continue the study of this operator\, generalizing previous results fo r the beta function and Wilson loop expectation value to the case of an ar bitrary representation of the gauge group and away from the planar limit. Focusing on the scalar ladder limit where the generalized Wilson loop redu ces to a purely scalar line operator in a free adjoint theory\, and\nspeci alizing to the case of the rank k symmetric representation of SU(N)\, we a lso study a certain ``semiclassical'' limit where k is taken to infinity w ith k \\zeta^2 fixed. This limit can be conveniently studied using a 1d de fect QFT representation in terms of path integral over N commuting 1d boso ns. Using this representation\, we compute the beta function and circular loop expectation value in the large k limit\, and use it to derive constra ints on the structure of the beta function for general representation. We discuss the corresponding 1d RG flow and comment on the consistency of th e results with the 1d defect version of the F-theorem.\n \nbased on joint work with Matteo Beccaria and Simone Giombi\n LOCATION:https://researchseminars.org/talk/LIJC/59/ END:VEVENT BEGIN:VEVENT SUMMARY:Juan Miguel Nieto García (Surrey U.\, Math. Stat. Dept.) DTSTART:20220203T144500Z DTEND:20220203T163000Z DTSTAMP:20260422T230723Z UID:LIJC/60 DESCRIPTION:Title: Jo rdan blocks and the Bethe ansatz: The eclectic spin chain as a limit\n by Juan Miguel Nieto García (Surrey U.\, Math. Stat. Dept.) as part of Lo ndon Integrability Journal Club\n\n\nAbstract\nIn this talk\, I will prese nt a procedure to extract the generalised eigenvectors of a non-diagonalis able matrix by considering a diagonalisable perturbation of it and computi ng the non-diagonalisable limit of its eigenvectors. As an example\, I wil l show how to compute a subset of the spectrum of the eclectic spin chain by computing the appropriate limit of the Bethe states of a twisted su(3) spin chain.\n LOCATION:https://researchseminars.org/talk/LIJC/60/ END:VEVENT BEGIN:VEVENT SUMMARY:David Vegh (Queen Mary\, U. of London) DTSTART:20220210T150000Z DTEND:20220210T163000Z DTSTAMP:20260422T230723Z UID:LIJC/61 DESCRIPTION:Title: Th e spectral curve of segmented strings\nby David Vegh (Queen Mary\, U. of London) as part of London Integrability Journal Club\n\n\nAbstract\nIn this talk\, I will discuss how to compute the spectral curve of ``segmente d strings'' in AdS_3. The motion of a string in this target space is integ rable and the worldsheet theory can be discretized while preserving integr ability. The corresponding embeddings are segmented strings\, which genera lize piecewise linear strings in flat space. I will present several exampl es. Next\, I will introduce ``brane tilings''\, which are doubly-periodic planar bipartite graphs. I will show that the motion of a closed segmented string can be embedded into the mutation dynamics of a certain brane tili ng. This will enable us to compute the spectral curve by taking the determ inant of the dressed adjacency matrix of the tiling.\n LOCATION:https://researchseminars.org/talk/LIJC/61/ END:VEVENT BEGIN:VEVENT SUMMARY:Gregory Korchemsky (IPhT Saclay) DTSTART:20220217T144500Z DTEND:20220217T163000Z DTSTAMP:20260422T230723Z UID:LIJC/62 DESCRIPTION:Title: Ap plications of strong Szego limit theorem in AdS/CFT\nby Gregory Korche msky (IPhT Saclay) as part of London Integrability Journal Club\n\n\nAbstr act\nI will review a recent progress in computing four-point correlation f unctions of infinitely heavy half-BPS operators in planar N = 4 SYM. Takin g advantage of integrability of the theory\, these correlation functions c an be constructed in terms of fundamental building blocks - the octagon fo rm factors. We show that the octagon form factor can be expressed as a Fre dholm determinant of an integrable Bessel operator and demonstrate that th is representation is very efficient in finding its dependence on the ’t Hooft coupling and two cross ratios. At weak coupling\, this yields a know n series representation of the octagon in terms of ladder integrals. At st rong coupling\, we apply strong Szego limit theorem to develop a systemati c expansion of the octagon in the inverse powers of the coupling constant and calculate accompanying expansion coefficients analytically.\n LOCATION:https://researchseminars.org/talk/LIJC/62/ END:VEVENT BEGIN:VEVENT SUMMARY:Joao Caetano DTSTART:20220224T144500Z DTEND:20220224T163000Z DTSTAMP:20260422T230723Z UID:LIJC/63 DESCRIPTION:Title: Cr osscap States in Integrable Theories\nby Joao Caetano as part of Londo n Integrability Journal Club\n\n\nAbstract\nIn this talk\, I will describe crosscap states in integrable field theories and spin chains in 1+1 dimen sions. I will derive an exact formula for overlaps between the crosscap st ate and any excited state in integrable field theories with diagonal scatt ering. I will then compute the crosscap entropy\, i.e. the overlap for the ground state\, in some examples. In the examples analyzed\, the result tu rns out to decrease monotonically along the renormalization group flow exc ept in cases where the discrete symmetry is spontaneously broken in the in frared. I will discuss crosscap states in integrable spin chains\, and obt ain determinant expressions for the overlaps with energy eigenstates. I wi ll comment on the realization of crosscap states in holography.\n LOCATION:https://researchseminars.org/talk/LIJC/63/ END:VEVENT BEGIN:VEVENT SUMMARY:Riccardo Borsato (Santiago de Compostela U.\, IGFAE) DTSTART:20220303T144500Z DTEND:20220303T163000Z DTSTAMP:20260422T230723Z UID:LIJC/64 DESCRIPTION:Title: Ho mogeneous Yang-Baxter deformations as undeformed yet twisted models\nb y Riccardo Borsato (Santiago de Compostela U.\, IGFAE) as part of London I ntegrability Journal Club\n\n\nAbstract\nI will review recent progress in the study of a class of integrable deformations of sigma models known as " homogeneous Yang-Baxter". These deformations can be understood as generali sations of the well known TsT transformations. In fact\, rather than defor mations\, the homogeneous Yang-Baxter procedure too can be reinterpreted a s imposing twisted worldsheet boundary conditions in the undeformed sigma model. I will explain how to construct the twist in the generic case\, whi ch generalises the twist of TsT from abelian to non-abelian. I will also u se the expression for the twist to discuss the construction of the classic al spectral curve in some examples. To conclude\, I will mention some open questions related to the quantum integrability of these models.\n LOCATION:https://researchseminars.org/talk/LIJC/64/ END:VEVENT BEGIN:VEVENT SUMMARY:Monica Guica DTSTART:20220317T144500Z DTEND:20220317T163000Z DTSTAMP:20260422T230723Z UID:LIJC/65 DESCRIPTION:by Monica Guica as part of London Integrability Journal Club\n \nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/LIJC/65/ END:VEVENT BEGIN:VEVENT SUMMARY:Troels Harmark DTSTART:20220324T144500Z DTEND:20220324T163000Z DTSTAMP:20260422T230723Z UID:LIJC/66 DESCRIPTION:by Troels Harmark as part of London Integrability Journal Club \n\nAbstract: TBA\n LOCATION:https://researchseminars.org/talk/LIJC/66/ END:VEVENT BEGIN:VEVENT SUMMARY:Shai M. Chester (Weizmann Inst.) DTSTART:20220310T144500Z DTEND:20220310T163000Z DTSTAMP:20260422T230723Z UID:LIJC/67 DESCRIPTION:Title: Bo otstrapping N = 4 super-Yang-Mills on the conformal manifold\nby Shai M. Chester (Weizmann Inst.) as part of London Integrability Journal Club\n \n\nAbstract\nWe study the N = 4 SYM stress tensor multiplet 4-point funct ion for any value of the complexified coupling tau\, and in principle any gauge group (we focus on SU(2) and SU(3) for simplicity). By combining non -perturbative constraints from the numerical bootstrap with two exact cons traints from supersymmetric localization\, we are able to compute upper bo unds on low-lying CFT data (e.g. the Konishi) for any value of tau. These upper bounds are very close to the 4-loop weak coupling predictions in the appropriate regime. We also give preliminary evidence that these upper bo unds become small islands under reasonable assumptions\, in which case our method would provide a numerical solution to N = 4 SYM for any gauge grou p and tau.\n LOCATION:https://researchseminars.org/talk/LIJC/67/ END:VEVENT END:VCALENDAR