Date : May 09, 2024
Speaker : Panagiotis Marinellis
Title :       [to be annouced]

 
Abstract :       

Date : May 02, 2024
Speaker : Zechuan Zheng
Title :         Bootstrap for Finite N Lattice Yang-Mills Theory

 
Abstract :       We introduce a comprehensive framework for analyzing finite N lattice YangMills theory and finite N matrix models. Utilizing this framework, we examine the bootstrap approach to SU(2) Lattice Yang-Mills Theory in 2,3 and 4 dimensions. The SU(2) Makeenko-Migdal loop equations on the lattice are linear and closed exclusively on single trace Wilson loops. This inherent linearity significantly enhances the efficiency of the bootstrap approach due to the convex nature of the problem, permitting the inclusion of Wilson loops up to length 24. The exact upper and lower margins for the free energy per plaquette, derived from our bootstrap method, demonstrate good agreement with Monte Carlo data, achieving precision within 0.1% for the physically relevant range of couplings in both three and four dimensions. Additionally, our bootstrap data provides estimates of the string tension, in qualitative agreement with existing Monte Carlo computations.

Date : Apr 11, 2024
Speaker : Pinaki Banerjee
Title :         Stringy Regge limit @1-loop

 
Abstract :        I'll talk about the high energy limit of 2 -> 2 strings scattering at 1-loop with fixed momentum transfer. This is known as the Regge limit. This limit is explored by two different methods : unitarity cuts and saddle-point analysis. Although standard Regge theory works for the closed string scattering, the  field theory intuition partially breaks down  for the open-string case, depending on the topology of the diagram. Furthermore, for the planar open-string scattering the leading contribution is simpler and can be extracted to arbitrary loop order.  When resummed in a certatin limit, it shows the leading Regge trajectory remains linear.  

Date : Apr 04, 2024
Speaker : Horatiu Nastase
Title :        3-point functions of currents for holographic cosmology and monopole non-Gaussianities

 
Abstract :        

Date : Mar 28, 2024
Speaker : Leonardo Pipolo de Gioia
Title :       Celestial amplitudes from Lorentzian conformal correlators

 
Abstract :        The Celestial Holography conjecture posits the existence of a codimension two theory capable of computing the S-matrix in a conformal primary basis. Although resembling a CFT in several respects, the intrinsic definition of this proposed dual theory remains elusive. In this talk, I will discuss a conjecture suggesting that Celestial CFT (CCFT) is related to a dimensionally reduced CFT on the Lorentzian cylinder and present some concrete examples of celestial amplitudes constructed in this way.

Date : Mar 21, 2024
Speaker : Murat Koloğlu
Title :         Quantum Detectorology 

 
Abstract :         I will talk about asymptotic detector operators describing possible measurements performed at null infinity. I will discuss how to define them in terms of light-ray operators, how to compute their matrix elements, and how to renormalize them in weakly-coupled field theories. I will apply this framework to Wilson-Fisher theory as an explicit example, recovering known results, resolving some puzzles, and discovering some novel findings about Regge trajectories. Finally, I will discuss detectors in asymptotically-flat Einstein gravity and present work in progress on the first computation of quantum 2- and 3-point energy correlators in a gravitational theory.

Date : Mar 21, 2024
Speaker : Vinícius Bernardes
Title :       A two parameter family of hyperbolic string vertices

 
Abstract :        String vertices are fundamental objects in string field theory: they define Feynman rules through a decomposition of the moduli space of Riemann surfaces. I will talk about a two-dimensional generalization of the hyperbolic string vertices, defined for both open and closed strings. For closed strings, this family provides an interpolation between the lightcone vertex (which is cubic but not Lorentz covariant), and the polyhedral vertices (which are covariant but not cubic).

Date : Mar 14, 2024
Speaker : Pietro Ferrero
Title :         On the supergravity description of non-critical string theories

Abstract :        We revisit the old question of how non-critical string theories can be used to study gauge theories using holography. To this end, focusing on supersymmetric cases, we first establish which gauged supergravity provides the correct "low energy" description for such string theories with a precise matching of the “massless” spectrum on a linear dilaton background. We then proceed to study supersymmetric solutions in gauged supergravity, which conjecturally represent configurations of D-branes of the non-critical string theory. These are supposed to provide the holographic dual of certain 3d and 4d gauge theories with eight supercharges, ranging from pure super Yang-Mills theory to super conformal QCD. The talk is based on work in progress with Leonardo Rastelli and Andrea Dei.

Date : Mar 14, 2024
Speaker : Rodrigo Pitombo
Title :       Towards the AdS Virasoro-Shapiro Amplitude

 
Abstract :         The Virasoro-Shapiro (VS) amplitude is the tree-level scattering amplitude between 4 massless closed strings and in AdS it is dual to a 4-point function of half-BPS operators to order 1/N^2. This is a hard problem in both sides of AdS/CFT as it involves non-perturbative physics in N=4 SYM and we don't yet know how to properly compute superstring amplitudes in AdS_5. In this talk, I will show how to properly define these amplitudes in terms of CFT correlators and review a series of papers by Fernando Alday and collaborators in which CFT bootstrap techniques are used together with a string-theory-inspired ansatz to completely fix the VS Amplitude to first order in a near-flat expansion.

References : https://arxiv.org/abs/2305.03593 , https://arxiv.org/abs/2204.07542 , https://arxiv.org/abs/2209.06223 , https://arxiv.org/abs/2306.12786

Date : Mar 07, 2024
Speaker : Pedro  Vieira
Title :        Fluids for Matrix Models for Huge Operators in AdS/CFT

 
Abstract :        

Date : Feb 29, 2024
Speaker : Nathan  Berkovits
Title :         On the equivalence of the pure spinor and Ramond-Neveu-Schwarz formalisms of the superstring

 
Abstract :        I will discuss the relation of the scattering amplitude prescriptions in the RNS and pure spinor superstring formalisms.

Date : Feb 01, 2024
Speaker : Dario Rosa
Title :         Describing large Hilbert spaces: from matrix product states to neural quantum states

 
Abstract :         We will review the standard problem in quantum many-body systems arising from the exponential growth of the Hilbert space with the number of particles, and we will discuss methods to deal with this challenge. At first, we will see how matrix product states allow to approximate states characterized by area-law entanglement. We will then turn to the recent proposal of neural quantum states as an effective way to approximate states characterized by volume law entanglement, that cannot be efficiently approximated with matrix product states.

Date : Nov 23, 2023
Speaker : Gabriel Menezes
Title :         Compton Scattering in String Theory

Abstract :         Scattering amplitudes and QFT methods have been applied successfully to understand in an alternative perspective the general relativistic two-body problem, notably in the calculation of the gravitational potential between two masses. In particular, classical contributions to the 2PM amplitude are controlled by the opposite-helicity Compton amplitude. However, it is well known that such amplitudes may develop unphysical poles when the spin of the massive particle exceeds the spin of the emitted messengers. In this talk we will explore the startling possibility that string theory may present an interesting solution to this issue.

Date : Nov 16, 2023
Speaker : Andrei Mikhailov
Title :       Yang-Mills algebra and symmetry transformations of vertex operators

Abstract :         Linearized solutions of SUGRA equations of motion are described in the pure spinor formalism by vertex operators. Under supersymmetry transformations, they transform covariantly only up to BRST exact terms. We identify the cohomology class which is responsible for that. Computations are simplified by using the formalism of quadratic algebras.

Date : Nov 01, 2023
Speaker : Eduardo Casali
Title : Flat space holography and twistors

Abstract :         

Date : Oct 26, 2023
Speaker : Alexey Sharapov
Title : Poisson electrodynamics and symplectic groupoids

Abstract :         Poisson electrodynamics represents the low-energy (or semi-classical) limit of the non-commutative U(1) gauge theory. I will present a new approach to Poisson electrodynamics based on the geometry of symplectic groupoids integrating a given Poisson manifold. From a physical point of view, a symplectic groupoid is just the phase space of a point particle in non-commutative space-time and gauge fields are identified with the group of bisections of a groupoid. The natural action of bisections on a symplectic groupoid allows one to define the minimal coupling of a charged particle with an electromagnetic field. Unlike usual classical mechanics, the momentum space of a particle appears curved (or even compact), which can lead to dramatic physical consequences.

Date : Oct 19, 2023
Speaker : João Gomide  
Title : B-RNS-GSS superstring in Ramond-Ramond backgrounds

Abstract :    The recently established B-RNS-GSS formalism shares features of the pure spinor, RNS and Green-Schwarz-Siegel formalisms for the superstring. Most notably, it has manifest spacetime supersymmetric and is quantized via a N=(1,1) worldsheet superconformal BRST charge with superconformal generators (G,T;Gbar,Tbar). In this talk, I will discuss recent work that extends this formalism to the description of Type II backgrounds by showing that the classical anticommutation relations {G,G}=-2T and {Gbar,Gbar}=-2Tbar recover the Type II supergravity equations of motion. As an application, I will also present an action and Lax connection for the string on an AdS_5xS^5 background.

Reference:   https://arxiv.org/abs/2310.02182

Date : Oct 05, 2023
Speaker : Connor Behan
Title : Recent progress in localization for non-Lagrangian theories

Abstract :    4d gauge theories with N=2 supersymmetry provide a rich playground for exact results as shown by Seiberg and Witten in 1994. Their techniques were significantly streamlined in the 2000s with the introduction of localization which operates directly on the path integral. Even more recently, localization has been combined with the conformal bootstrap thereby shedding light on unprotected operators. A natural next step is to apply this, not just to gauge theories themselves, but to infrared phases of these theories which live at singular points of the moduli space. The fact that these CFTs are non-Lagrangian brings additional challenges which are the focus of the recent paper I will discuss. 

Reference :      https://arxiv.org/abs/2306.05141

Date : Sep 14, 2023
Speaker : Andres Anabalon
Title : Supersymmetric AdS Solitons

Abstract :  I will discuss a recent generalization of the AdS Soliton to support nontrivial Killing Spinors.  Based on :

1.  Supersymmetric solitons and a degeneracy of solutions in AdS/CFT  

2. Supersymmetric solitons in gauged $\mathcal{N}=8$ supergravity