Link to the (inofficial) DESY hep-th seminar calendar
The journal club takes place on Tuesdays from 13:30 to 15:00 in Seminar Room SR7a (building 7, behind the canteen).
Paper discussions consist of ~10 minutes of short informal presentation followed by another ~10 minutes of discussion.
We collect papers suggested for discussion in a shared document (link via email). Please add anything you find interesting to that list!
2403.13877.pdf
(Florent Baume)
Alday, Chester, Hansen, Zhong: The AdS Venziano
amplitude at small curvature
2403.13050.pdf
(Deniz Bozkurt)
Zoltan Bajnok, Bercel Boldis and Gregory
Korchemsky: Tracy-Widom distribution in four-dimensional super
Yang-Mills theories
2403.14544.pdf
(Antonio Antunes)
Mazel, Sandor, Wang, Yin: Conformal Perturbation
Theory and Tachyon-Dilaton Eschatology via String Fields
2402.02584.pdf
(Federico Ambrosino)
Verlinde, Zhang: SYK Correlators from 2D
Liouville-de Sitter Gravity
2403.10772.pdf
(Alessio Miscioscia)
He, Kruczenski: Gauge theory bootstrap: Pion
amplitudes and low-energy parameters
2312.05221.pdf
(Julien Barrat)
Bianchi, Bonomi, de Sabbata, Gimenez-Grau: Analytic
bootstrap for magnetic impurities
2403.04835.pdf
(Federico Ambrosino)
Copetti, Komatsu, Cordova: Non-Invertible
Symmetries, Anomalies and Scattering Amplitudes
2403.07079.pdf
(Sebastian Harris)
Fardelli, Fitzpatrick, Li: Holography and Regge
Phases with U(1) Charge
2401.10981.pdf
(Carlos Bercini)
Antonio Padilla and Robert G. C. Smith: Smoothed
asymptotics: from number theory to QFT
2402.14787.pdf
(Felix Tellander)
Helmer, Papathanasiou, Tellander: Landau
Singularities from Whitney Stratifications
2312.12510.pdf
(Lorenzo Mansi)
Mansi, Sperling: Unravelling T-Duality: Magnetic
Quivers in Rank-zero Little String Theories
2403.02379.pdf
(Juan Miguel Nieto Garcia)
Fontanella, Nieto Garcia: Constructing
Non-Relativistic AdS5/CFT4 Holography
2402.19358.pdf
(Florent Baume)
Perlmutter: A Rigorous Holographic Bound on AdS
Scale Separation
2401.10986.pdf
(Sebastian Harris)
Harris, Kaviraj, Mann, Quintavalle, Schomerus:
Comb Channel Lightcone Bootstrap II: Triple-Twist Anomalous
Dimensions
2311.10814.pdf
(Gabriele Dian)
Arkani-Hamed, Flieger, Henn, Schreiber, Trnka:
Coulomb Branch Amplitudes from a Deformed Amplituhedron Geometry
2312.09308.pdf
(Alessio Miscioscia)
Karateev, Penedones, Komargodski, Sahoo: Trace
Anomalies and the Graviton-Dilaton Amplitude
2401.06099.pdf
(Carlos Bercini)
Bercini, Fernandes, Goncalves: Two loop five point
integrals: light, heavy and large spin correlators
2401.06818.pdf
(Antonio Antunes)
Antunes, Lauria, Rees: A bootstrap study of
minimal model deformations
2401.05207.pdf: Gabriele Dian, Paolo Benincasa: The Geometry of Cosmological Correlators
Abstract: Energy-Energy Correlators (EECs) have emerged as powerful tools for collider QCD with applications ranging from decoding the hadronic energy flux in jets, resolving scales in heavy ion collisions to precision measurements of the strong coupling and the top quark mass. There is already a strong experimental effort behind their measurements at the LHC, RHIC and upcoming collider facilities, such as the EIC. What is particularly exciting about them is their strong links with highly developed techniques from CFTs, in particular, the recent advancements in the study of light-ray operators and their OPE. Moreover, their computation has involved applications of cutting-edge techniques from Feynman integrations and has uncovered intriguing connections with scattering amplitudes.
In this overview talk, I will review recent advancements in the study of EECs from the perspective of jet substructure, while highlighting along the way some of these connections with formal theory and Feynman integration techniques. The goal of this talk is to initiate a discussion between theorists spread across these varied disciplines, hopefully leading to a fruitful cross-talk.
Pedro will lead a discussion of 2108.09330.pdf: Kantor, Niarchos, Papageorgakis: Conformal Bootstrap with Reinforcement Learning, and possibly other related papers.
Abstract: I’ll review recent progress in understanding the O(n) (for n complex) CFTs in two dimensions. These theories have important applications in physics and mathematics, but resisted understanding until recently, where the bootstrap method, combined with insights from representation theory, made possible an (almost) complete exact solution.
2211.11791.pdf: Simon Caron-Huot: Holographic Cameras: An Eye for the Bulk
Simmons-Duffin
lecture notes
1509.00014.pdf: Thomas
Hartman, Sachin Jain, Sandipan Kundu: Causality Constraints in Conformal
Field Theory
Abstract: One of the attractive properties of QFT with extended supersymmetry is the existence of families of local operators described by tractable algebraic structures, like chiral and topological algebras. The corresponding correlation functions are often computable and strongly constrain the dynamics of the theory. In this talk, I will combine this type of construction with BPS line defects in the context of 3d N=4 QFTs, preserving a fraction of the supersymmetry. From that, I will derive an exact formula for correlation functions of an arbitrary number of conserved current multiplets with line defects. As a concrete example, I will apply this method in the case of the 1/2-BPS Wilson line in ABJM and combine it with localization leading to an alternative formula for the bremsstrahlung and to the first results for the two-point function of the stress tensor multiplet.
2210.15694.pdf: Cuomo, Komargodski: Giant Vortices and the Regge Limit
2211.12555.pdf: Basso, Dixon, Liu, Papathanasiou: An origin story for amplitudes
2212.09758.pdf: Cota, Mininno, Weigand, Wiesner: The Asymptotic Weak Gravity Conjecture in M-theory
2211.12555.pdf: Basso, Dixon, Liu, Papathanasiou: An origin story for amplitudes
2110.04364.pdf:
Bercini, Goncalves, Homrich, Vieira: The Wilson Loop - Large Spin OPE
Dictionary
2207.08931.pdf: Bercini,
Goncalves, Homrich, Vieira: Spinning Hexagons
2210.01135.pdf: Clay Córdova, Diego García-Sepúlveda: Symmetry Enriched c-Theorems & SPT Transitions
Abstract: Defects that break a global symmetry group are endowed with exactly marginal defect operators, which allow to deform a CFT along the defect conformal manifold, which is the symmetry breaking coset. Its Zamolodchikov metric is expressed as the 2-pt function of the exactly marginal operator and the Riemann tensor can be expressed as an integrated 4-pt functions. I will give examples on the cases of the 1/2 BPS Maldacena-Wilson loop in N=4 SYM, and the 1/2 and 1/3 BPS Fermionic Wilson in ABJM.
Abstract: Tremendous progress has been achieved during the last years in bootstrapping conformal correlators at strong coupling using analytical bootstrap methods and the AdS/CFT correspondence. In particular, the development of Lorentzian inversion formulae revealed helpful in reconstructing four-point functions. In this talk I will present how this technology can be adapted to defect setups in order to compute scalar two-point functions in the presence of a conformal defect in the strong-coupling regime. We derived a dispersion relation that allows to efficiently generate elegant closed-form expressions for a variety of setups, and in particular we apply this method to two-point functions of single-trace half-BPS operators in the presence of the supersymmetric Wilson line defect in 4d N=4 SYM, using minimal input from holography.
Abstract: Almost 50 years after its formulation, the ‘t Hooft model, describing a two-dimensional version of QCD in the Large N limit, still represents a very rich toy model and is now getting renewed attention both from a gauge and string theory perspective. The mesonic bound states are the simplest objects of this confining theory and the spectrum thereof has been thoroughly studied in the early literature by means of numerical methods. Yet, there has been a substantial lack of analytical results in merit. The goal of this talk, based on an upcoming paper of the speaker and S. Komatsu, is trying to fill this gap by presenting analytical results for the mesons spectral problem that illustrate an interesting and rich integrability structure that underlies the problem and that can be used to analytically solve it. Namely, employing some integral transformations, a set of TQ-Baxter relations can be derived and, through them, it is possible to construct a series representation for mesons’ masses and wavefunctions that is valid for every given mass of their quark constituents. This extends the seminal work 0905.2280 by Zamolodchikov and collaborators that only treated a specific value for them. Finally, 3- and 4-point scattering amplitudes of mesons will be discussed as well as some further applications of this formalism.
Abstract: The Skyrme model is a nonlinear field theory of nuclei which acts as a low-energy effective theory for QCD. The Skyrme model admits topological soliton solutions called skyrmions, which are physically identified with baryons. The Skyrme field equations do not allow for exact solutions, so over the years this has prompted several approximate descriptions to complement numerical simulations, and to allow a quantum treatment. One attempt (originally due to Atiyah and Manton) approximates skyrmions with the holonomy of Yang-Mills instantons. Although seemingly ad hoc, this approach is remarkably accurate. Recently, an holographic understanding due to Sutcliffe has explained its accuracy, putting the instanton approximation into a framework which is controlled, and not ad hoc, and allows for generalisation. In this talk, I will provide a survey of the instanton approximation. In particular I shall discuss some recent work of myself (joint with various collaborators) on how the instanton approximation can be generalised to study electromagnetic effects in the Skyrme model in a more realistic way to earlier attempts, and how to push the ordinary instanton approximation further to gain greater insights into quantum properties of skyrmions.
Abstract: We consider the N=2 SYM theory with gauge group SU(N) and a matter content consisting of one multiplet in the symmetric and one in the anti-symmetric representation of the gauge group. This theory is conformal and it admits a large-N ’t Hooft expansion and a gravity dual given by a particular orientifold of AdS_5 x S^5. We analyze this theory relying on the matrix model provided by localization à la Pestun. Even if this matrix model has very non-trivial interactions, by exploiting the full Lie algebra approach to the matrix integration, we show that a large class of observables can be expressed in a closed form in terms of an infinite matrix depending on the ’t Hooft coupling lambda. These exact expressions can be used to generate the perturbative expansions at high orders and also to analytically study the leading behavior at strong coupling. Finally we compare these predictions to a direct Monte Carlo numerical evaluation of the matrix integral and to the Padé resummation derived from very long perturbative series. Depending on time we also discuss the generalization of these results for a circular quiver gauge theory and the corresponding holographic interpretation
Three-point functions in a superconformal gauge theory and their strong-coupling limit: 2202.06990.pdf
Strong-coupling results for superconformal quivers and holography: 2109.0055.pdf
Exact results in a N=2 SCFT at strong coupling: 2105.15113.pdf
Abstract: In recent years, it has been found that cluster algebra plays important roles in analyzing and predicting singularities of amplitudes and Feynman integrals. In this talk, we identify cluster algebras for planar kinematics of conformal Feynman integrals in four dimensions, as sub-algebras of that for top-dimensional G(4,n) corresponding to n-point massless kinematics. We provide evidence that they encode information about singularities of such Feynman integrals, including all-loop ladders with symbol letters given by cluster variables and algebraic generalizations. As a highly-nontrivial example, we apply the method to an n=8 three-loop wheel integral, which contains a new square root, and bootstrap its result. By sending a point to infinity, our results have implications for non-conformal Feynman integrals. 2112.11842.pdf
Abstract: Recently, experimentalists have been using Rydbery atoms arranged on different lattices to realize exotic phases (and phase transitions) of condensed matter systems, such as the Z2 spin liquid phase. The systems can sometimes be mapped onto quantum dimer models, which can be simulated using quantum monte carlo techniques. What’s more, the low energy excitations of the system are described by scalar phi^4 theory. Some of the phases transitions of Rydbery atoms arrays are therefore described by the famous Wilson-Fisher CFTs. The talk is based on 2205.04472.pdf
Abstract: We consider correlation functions of single trace operators approaching the cusps of null polygons in a double-scaling limit where so-called cusp times t_i^2 = g^2 log(x_{i−1,i}^2) log(x_{i,i+1}^2) are held fixed and the t’Hooft coupling is small. With the help of stampedes, symbols and educated guesses, we find that any such correlator can be uniquely fixed through a set of coupled lattice PDEs of Toda type with several intriguing novel features. These results hold for most conformal gauge theories with a large number of colours, including planar N=4 SYM.
The talk is based on 2111.12131.pdf and 2205.04476.pdf
Abstract: We find a two-parameter family of solutions of the Yang-Mills equations for gauge group SO(1,3) on Minkowski space by foliating different parts of it with non-compact coset spaces with SO(1,3) isometry. The interior of the lightcone is foliated with hyperbolic space H3≅SO(1,3)/SO(3), while the exterior of the lightcone employs de Sitter space dS3≅SO(1,3)/SO(1,2). The lightcone itself is parametrized by SO(1,3)/ISO(2) in a nilpotent fashion. Equivariant reduction of the SO(1,3) Yang-Mills system on the first two coset spaces yields a mechanical system with inverted double-well potential and the foliation parameter serving as an evolution parameter. Its known analytic solutions are periodic or runaway except for the kink. On the lightcone, only the vacuum solution remains. The constructed Yang-Mills field strength is singular across the lightcone and of infinite action due to the noncompact cosets. Its energy-momentum tensor takes a very simple form, with energy density of opposite signs inside and outside the lightcone.