Talks

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Nonperturbative and Numerical Approaches to Quantum Gravity, String Theory and Holography (Hybrid)
Monday, 22 August 2022
Time Speaker Title Resources
09:45 to 10:00 Rajesh Gopakumar (ICTS, Bengaluru, India) Welcome address
10:00 to 11:15 Anna Hasenfratz (University of Colorado, USA) Introduction to Lattice Field Theory

 This lecture will provide a basic summary of gauge theories on the lattice, including discussion of universality of actions, observables, and taking the continuum limit
 
11:45 to 13:00 David Berenstein (University of California, USA) An introduction to the AdS/CFT correspondence (Lecture 1)

I will describe some of the basic elements of the AdS/CFT correspondence. These include a motivation for it, some of the aspects of  representation theory of the conformal group, states in CFT and their AdS duals. I will also explain the extrapolate dictionary and how to think about bulk reconstruction from the boundary.

Useful material to read:

https://arxiv.org/abs/hep-th/9711200
https://arxiv.org/abs/hep-th/9802150
https://arxiv.org/abs/hep-th/0606141
https://arxiv.org/abs/1411.7041
 
14:30 to 15:45 David Schaich (University of Liverpool, UK) Lattice supersymmetric Field Theories (Lecture 1)

Lattice field theory provides a non-perturbative regularization suitable for strongly interacting systems, which has proven crucial to the study of quantum chromodynamics among many other theories.  Lattice investigations of supersymmetric field theories have a long history but often struggle due to the interplay of supersymmetry with the lattice discretization of space-time.  I will review these issues and recent progress overcoming them, with particular focus on maximally supersymmetric Yang--Mills theories that play important roles in holography.
 
   
16:15 to 17:30 Martin Kruczenski (Purdue University, USA) Two applications of the bootstrap in QCD.

First, I am going to describe bootstrap methods applied to the loop equation in Lattice QCD (pure YM theory). Second I am going to consider the S-matrix bootstrap applied to the computation of S-matrices in the 2d non-linear sigma model,  a toy model for QCD. Finally I am going to consider applications of the S-matrix bootstrap to meson scattering.
     
17:45 to 18:30 - Discussions/ Questions on Lectures
Tuesday, 23 August 2022
Time Speaker Title Resources
10:00 to 11:15 Anna Hasenfratz (University of Colorado, USA) Introduction to Wilsonian renormalization group

This lecture will continue the discussion of Lecture One about universal properties of lattice models, following the powerful steps of Wilsonian renormalization group.
 
11:45 to 13:00 David Berenstein (University of California, USA) An introduction to the AdS/CFT correspondence (Lecture 2)

I will describe some of the basic elements of the AdS/CFT correspondence. These include a motivation for it, some of the aspects of  representation theory of the conformal group, states in CFT and their AdS duals. I will also explain the extrapolate dictionary and how to think about bulk reconstruction from the boundary.

Useful material to read:

https://arxiv.org/abs/hep-th/9711200
https://arxiv.org/abs/hep-th/9802150
https://arxiv.org/abs/hep-th/0606141
https://arxiv.org/abs/1411.7041
 
14:30 to 15:45 Martin Kruczenski (Purdue University, USA) Two applications of the bootstrap in QCD (Lecture 2)

First, I am going to describe bootstrap methods applied to the loop equation in Lattice QCD (pure YM theory). Second I am going to consider the S-matrix bootstrap applied to the computation of S-matrices in the 2d non-linear sigma model,  a toy model for QCD. Finally I am going to consider applications of the S-matrix bootstrap to meson scattering.

 
     
16:15 to 17:30 Mithat Unsal (NC State University, USA) Semi-Classics, Adiabatic Continuity and Resurgence in Quantum Theories (Lecture 1)
   
17:45 to 18:30 - Discussions/ Questions on Lectures
Wednesday, 24 August 2022
Time Speaker Title Resources
10:00 to 11:15 David Schaich (University of Liverpool, UK) Lattice supersymmetric field theories (Lecture 2)

Lattice field theory provides a non-perturbative regularization suitable for strongly interacting systems, which has proven crucial to the study of quantum chromodynamics among many other theories. Lattice investigations of supersymmetric field theories have a long history but often struggle due to the interplay of supersymmetry with the lattice discretization of space-time. I will review these issues and recent progress overcoming them, with particular focus on maximally supersymmetric Yang--Mills theories that play important roles in holography.
   
11:45 to 13:00 David Berenstein (University of California, USA) An introduction to the AdS/CFT correspondence (Lecture 3)

I will describe some of the basic elements of the AdS/CFT correspondence. These include a motivation for it, some of the aspects of  representation theory of the conformal group, states in CFT and their AdS duals. I will also explain the extrapolate dictionary and how to think about bulk reconstruction from the boundary.

Useful material to read:

https://arxiv.org/abs/hep-th/9711200
https://arxiv.org/abs/hep-th/9802150
https://arxiv.org/abs/hep-th/0606141
https://arxiv.org/abs/1411.7041
 
14:30 to 15:45 Martin Kruczenski (Purdue University, USA) Two applications of the bootstrap in QCD (Lecture 3)

 First, I am going to describe bootstrap methods applied to the loop equation in Lattice QCD (pure YM theory). Second I am going to consider the S-matrix bootstrap applied to the computation of S-matrices in the 2d non-linear sigma model,  a toy model for QCD. Finally I am going to consider applications of the S-matrix bootstrap to meson scattering.
     
16:15 to 17:30 Kostas Skenderis (University of Southampton, UK) An introduction to gauge/gravity duality and holographic renormalization (Lecture 1)

Introduction to gauge/gravity duality and the holographic dictionary. Introduction to Anti-de Sitter (AdS) spacetime, Asymptotically locally AdS spacetimes and Fefferman-Graham coordinates.

Resources: hep-th/0209067, hep-th/0404176, 0812.2909
 
17:45 to 18:30 - Discussions/ Questions on Lectures
Thursday, 25 August 2022
Time Speaker Title Resources
10:00 to 11:15 Anna Hasenfratz (University of Colorado, USA) Gradient flow and its application (Lecture 3)

Gradient flow is an operation that removes ultraviolet fluctuation. It has been widely used in Lattice QCD calculations. In this lecture I will connect it to Wilsonian renormalization group and discuss applications like calculating the nRG beta function non-perturbatively, the QCD Lambda parameter, and renormalization of composite operators.
 
11:45 to 13:00 David Schaich (University of Liverpool, UK) Lattice Supersymmetric Field Theories (Lecture 3)

Lattice field theory provides a non-perturbative regularization suitable for strongly interacting systems, which has proven crucial to the study of quantum chromodynamics among many other theories. Lattice investigations of supersymmetric field theories have a long history but often struggle due to the interplay of supersymmetry with the lattice discretization of space-time. I will review these issues and recent progress overcoming them, with particular focus on maximally supersymmetric Yang--Mills theories that play important roles in holography.
   
14:30 to 15:45 Kostas Skenderis (University of Southampton, UK) An introduction to gauge/gravity duality and holographic renormalization (Lecture 2)

Holographic computation of correlation functions, and holographic renormalization. Radial Hamiltonian formulation. Application to 3d gravity.
 
16:15 to 17:30 Mithat Unsal (NC State University, USA) Semi-Classics, Adiabatic Continuity and Resuregence in Quantum Theories (Lecture 2)
   
17:45 to 18:30 - Discussions/ Questions on Lectures
Friday, 26 August 2022
Time Speaker Title Resources
10:00 to 10:30 Richard Brower (Boston University, USA) Quantum Finite Elements: Lattice Field Theory on Curved Manifolds.

The problem of reformulating Euclidean lattice field theory  on a simplicial complex targeted to a general curved Riemann manifolds is presented.  The Finite Elements Method with the use of Discrete Exterior Calculus (DEC) allows for the full solution for any free CFT on any Riemann manifold. However non-perturbative quantum physics requires a  modification , referred to as Quantum Finite Elements (QFE), with localmetric dependent counter terms.

Monte Carlo simulation for phi^4 give accurate Ising data in 2d on a Riemann sphere (S2)  and for 3d for radial quantization on R x S2 at the Wilson Fisher fixed point.  The solution of the Affine Ising model gives a solution to general modular torus and suggest a  non-perturbative map to the tangent plane  of Riemann manifolds that remove the need for perturbative counter terms.
   
10:30 to 11:00 Raghav Jha (Perimeter Institute for Theoretical Physics, Canada) Some old problems on the lattice using tensors

We apply the approximate real-space renormalization group methods based on tensor networks to study models with discrete and continuous symmetries in three dimensions. If time permits, we will also discuss the matrix product state (MPS) approach to scattering in Ising Field theory (IFT) in two dimensions around and away from the two integrable limits. The talk is based partially on https://arxiv.org/abs/2105.08066 and upcoming work.

 
 
11:45 to 12:15 Denjoe O’Connor (Dublin Institute for Advanced Studies, Ireland) The Hagedorn transition in the Bosonic BFSS Model Revisited

I will review the Bosonic BFSS model and present new results on its spectrum. I will show that matrix trace relations are negligible up to matrix products of length $N^2/4$ and dominate thereafter. This universal result allows the finite $N$ corrections to the Hagedorn transition to be understood in detail. I will also justify why one should expect a gauge Gaussian approximation to capture the low energy properties of the model.
 
14:30 to 15:45 Kostas Skenderis (University of Southampton, UK) An introduction to gauge/gravity duality and holographic renormalization (Lecture 3)

Real-time gauge/gravity duality. Out-of-equilibrium QFT and gauge/gravity duality.
 
16:15 to 17:30 Mithat Unsal (NC State University, USA) Semi-Classics, Adiabatic Continuity and Resuregence in Quantum Theories (Lecture 3)
   
17:45 to 18:30 - Discussions/ Questions on Lectures
Saturday, 27 August 2022
Time Speaker Title Resources
10:00 to 10:30 Vaibhav Gautam (University of Surrey, UK) Matrix Entanglement

In gauge/gravity duality, matrix degrees of freedom on the gauge theory side play important roles for the emergent geometry. In this paper, we discuss how the entanglement on the gravity side can be described as the entanglement between matrix degrees of freedom. We consider several classes of quantum states to which our approach can play important roles. When applied to fuzzy sphere, matrix entanglement can be used to define the usual spatial entanglement in two-brane or five-brane world-volume theory nonperturbatively in a regularized setup. Another application is to a small black hole in AdS_5 X S^5 that can evaporate without being attached to a heat bath, for which our approach suggests a gauge theory origin of the Page curve. The confined degrees of freedom in the partially-deconfined states play the important roles.
 
10:30 to 11:00 Arpith Kumar (IISER Mohali, India) Complex Langevin study of spontaneous SO(10) symmetry breaking in Euclidean IKKT matrix model

The IKKT matrix model in the large-N limit is conjectured to be a non-perturbative definition of the ten-dimensional type IIB superstring theory. Due to the Pfaffian's inherently complex nature upon Euclideanization, the model has a severe sign problem. The phase of the Pfaffian plays a critical role in determining the correct vacuum of the model. In recent years, the complex Langevin method has successfully tackled the sign problem. In this talk, we will discuss our preliminary results from the complex Langevin simulations of the Euclidean version of the IKKT model. We investigate the possibility of spontaneous breaking of rotational symmetry. The model must be deformed to evade the singular drift problem during complex Langevin simulations. We recover the original model in the limit of vanishing deformation parameters. Instead of mass deformations that explicitly break supersymmetry, we introduce supersymmetry-preserving deformations with a Myers term. We conclude that the phase of the Pfaffian indeed induces the spontaneous SO(10) symmetry breaking in the Euclidean IKKT model.
   
11:00 to 11:30 Hiromasa Watanabe (KEK, Japan) Partial deconfinement in large N gauge theory

We will argue the confinement/deconfinement phase transition in large N gauge theory at finite temperature. In the context of deconfinement, a coexisting phenomenon in the color space called partial deconfinement has been found and discussed recently. The coexisting phase appears in the intermediate region separated by two phase-transition points at large N, the Hagedorn and the Gross-Witten-Wadia phase transitions, and its properties can be expressed by contributions from both the confined and deconfined sectors. In the talk, we will review its description, motivations partly from the gauge/gravity duality, and applications, by showing the previous analytical and numerical evidence of partial deconfinement.
 
11:45 to 18:30 - Discussions
Sunday, 28 August 2022
Time Speaker Title Resources
10:00 to 18:45 - Discussions
Monday, 29 August 2022
Time Speaker Title Resources
10:00 to 10:30 Shailesh Chandrasekharan (Duke University, USA) A simple Qubit Regularization Scheme for SU(N) Lattice Gauge Theories

We introduce a simple lattice regularization scheme for SU(N) lattice gauge theories with matter in the fundamental representation. We explain how gauge invariant subspaces can be constructed in various spatial dimensions within this scheme. We explicitly construct examples of gauge invariant subspaces in one and two dimensions for N=2,3. For suitably chosen Hamiltonians, our regularization scheme allows us to explore the physics of both confined and deconfined phases.

Study Material:

The work discussed here is an extension of the work published in:

Symmetry, 14 (2022) 2, 305, arXiv:2112.02090
 
10:30 to 11:00 David Schaich (University of Liverpool, UK) Lattice studies of three-dimensional super-Yang--Mills

I will present ongoing lattice investigations of supersymmetric Yang--Mills (SYM) theories in three space-time dimensions, focusing on the maximal case with Q=16 supercharges and also including work in progress on Q=8 SYM.  While this talk will refer to the lattice supersymmetry lectures in the first week of the program, it will remain largely self-contained.
 
   
11:45 to 12:15 Antonio Gonzalez-Arroyo (Institute of Theoretical Physics - IFT, Spain) Recent Results on Twisted Matrix Models

Twisted matrix models are equivalent to large N field theories and offer a very efficient tool to obtain perturbative and non-perturbative information about them. After a brief overview we will focus on recent  results obtained in their application to
Supersymmetric gauge theories.
 
12:15 to 12:45 Stratos Pateloudis (University of Regensburg, Germany) The Low Temperature Regime of the D0-brane Matrix Model

I will describe the low energy limit of the D0-matrix models and their gravitational interpretations. I will show that in low energies it is possible to obtain a confined, stable phase in the matrix model and how this is interpreted as a gas of supergravitons in 11D spacetime, following motivation from the usual holography. This confinement/deconfinement transition is interpreted as a topology change in the gravity side. Stable phases can be studied at low temperatures and to this end, I will be using the deformed D0-matrix model (BMN). I will argue that the role of the singlet and non-singlet sectors in the contributions to the partition functions are almost the same in these low temperatures providing numerical verifications. In addition, I will compare numerical results from the matrix model with the internal energy of the analytically known black zero-brane at low temperatures where one can better test the gauge/gravity duality with small stringy corrections. This way we are in a position to better test the gauge/gravity duality when both sides are computable. 

Based on 2110.01312, 2205.06098 and on-going work
 
14:30 to 15:00 Kostas Skenderis (University of Southampton, UK) Lattice holographic cosmology and the renormalization of the 2-point function of the energy-momentum tensor on the lattice

In holographic cosmology the very early universe is modelled holographically using a 3d QFT (without gravity) and cosmological observables are obtained by computing corresponding QFT observables. In particular, in order to obtain the cosmological power spectrum we need to compute the 2-point function of the energy momentum of the QFT. In Lattice holographic cosmology the QFT observables are computed using Lattice methods. In this talk I will discuss the status of the computation of the 2-point function of the energy momentum on the lattice. In particular, I will discuss how to define the energy-momentum tensor and how to renormalize the 2-point function.

Based on 2009.14767, 2009.14768 and on-going work.
 
15:00 to 15:30 Ning Su (University of Pisa, Italy) The hybrid conformal bootstrap

Three dimensional conformal field theories(CFTs) describe important critical physics in the real world. In the past few years much progress has been made in 3D CFTs using the conformal bootstrap. In particular, using numerical bootstrap, the critical exponents of the 3D Ising, Super-Ising, O(2), O(3) CFTs have been determined precisely with rigorous error bars, while using analytic bootstrap, the information of the leading twist operators at large spins can be computed analytically. The two bootstrap approaches are sensitive to different regions of the spectrum and complement each other. In this talk, I will first give a general review of the numerical bootstrap and analytic bootstrap. Then I will discuss how to combine the numerical bootstrap with the analytic lightcone bootstrap, i.e. a hybrid bootstrap method. As a result, the bootstrap prediction for the actual CFT can be significantly improved.
 
16:00 to 16:30 Masaki Tezuka (Kyoto University, Japan) Binary-coupling sparse Sachdev-Ye-Kitaev model

The sparse version of the Sachdev-Ye-Kitaev (SYK) model has been studied in the last few years, where only $\mathcal{O}(N)$ random couplings are activated out of the $\mathcal{O}(N^4)$ possible 4-fermion couplings for $N$ fermions.
Here we propose a further simplification and improvement of the model, which we call the binary-coupling sparse SYK model. We set the non-zero couplings to be $\pm 1$, rather than being sampled from a continuous distribution such as Gaussian.
The spectral statistics of the energy spectrum, including the gap ratio and the spectral form factor, indicates that our choice generates correlation in the spectrum more efficiently in terms of the number of non-zero terms. This work (arXiv:2208.12098) has been done in collaboration with Onur Oktay, Enrico Rinaldi, Masanori Hanada, and Franco Nori.
   
16:30 to 17:00 Pau Figueras (Queen Mary University of London, UK) The Gregory-Laflamme instability of black strings revisited

In this talk I will discuss our recent work that reproduces and extends the famous work of Lehner and Pretorius on the end point of the Gregory-Laflamme instability of black strings. We consider black strings of different thicknesses and our numerics allow us to get closer to the singularity than ever before. In particular, while our results support the picture of the formation of a naked singularity in finite asymptotic time, the process is more complex than previously thought. 

Reading materials:
 
17:00 to 17:30 Agnese Bissi (Uppsala universitet, Sweden) A CFT perspective on AdS amplitudes

In this talk I will discuss how to construct loop amplitudes on AdS spaces using the AdS/CFT correspondence and the conformal bootstrap.
 
17:45 to 18:15 Mithat Unsal (NC State University, USA) Adiabatic Continuity,anomaly preserving compactifications and confinements in Yang-Mills theroy
 
18:15 to 18:45 Ryo Sakai (Syracuse University, USA) Improved coarse-graining methods on two dimensional tensor networks including fermions

Tensor renormalization group (TRG) has attractive features like the absence of sign problems and the accessibility to the thermodynamic limit, and many applications to lattice field theories have been reported so far. However it is known that the TRG has a fictitious fixed point that is called the CDL tensor and that causes less accurate numerical results. There are improved coarse-graining methods that attempt to remove the CDL structure from tensor networks. Such approaches have been shown to be beneficial on two dimensional spin systems. We discuss how to adapt the removal of the CDL structure to tensor networks including fermions, and numerical results that contain some comparisons to the plain TRG, where significant differences are found, will be shown.
Tuesday, 30 August 2022
Time Speaker Title Resources
10:00 to 11:15 Georg Bergner (University of Jena, Germany) Matrix Models, Gauge-Gravity Duality, and Simulations on the Lattice (Lecture 1)
 
11:45 to 13:00 Daisuke Kadoh (Doshisha University, Japan) An Introduction to Tensor Renormalization Group (Lecture 1)
 
14:30 to 15:00 N.D. Hari Dass (TIFR, Hyderabad, India) Pure Gauge Flux Tubes and Effective Strings.

The main finding of my numerical work with Pushan Majumdar was that the static QQ ̄ -potentials for both D = 4 SU(3), and D = 3 SU(2) for large separations, as measured on the lattice by high precision polyakov-loop correlators, is well described by V (R) = σ R −(D−2)π 24R − (D−2)2π 2 1152σ R3 . . .. Remarkably, this is also the 1 R expansion of the ground state energy of the Bosonic String as derived by Arvis. The mystery of why a formula meant to hold in D = 26 works so well in d = 3, 4 was resolved by Peter Matlock and myself on the basis of Polchinski-Strominger effective string theories. Further developments of this effective string theory, including a covariant calculus for them, and important open issues will also be highlighted.
 
15:00 to 15:30 Junggi Yoon (APCTP, South Korea) Does Negative Central Charge always Imply Non-unitarity?

In this talk, I will discuss a simple quantum mechanical toy model which seemingly has negative norm state. I will show that a new inner product can cure the the negative norm problem. Then I will discuss Hermiticity of Hamiltonian and unitarity of the model. Based on this example, I will explain how 2D free symplectic fermion with negative central charge can be unitarity. Also I will explain alpha-vacua of the symplectic fermion, and I will compare them with alpha vacua of de Sitter space.
 
16:00 to 16:30 Indrakshi Raychowdhury (BITS Pilani K K Birla Goa Campus, India) Loop-String-Hadron dynamics in a SU(3) lattice gauge theory.

In this talk, I will present a key step toward quantum simulating QCD. A particular framework of the Hamiltonian formalism is itself an important design decision, where factors to consider include (non)locality of the degrees of freedom, (non)Abelian constraints, and computational costs associated with simulating the Hamiltonian. The novel loop-string-hadron(LSH) framework developed for SU(2) features a set of benefits. This work represents the generalization of the original SU(2) construction to SU(3) (in 1+1 dimensions) and the associated costs and benefits that are crucial for practical implementation.
   
16:30 to 17:00 Junyu Liu (University of Chicago, USA) Neural Tangent Kernel theory from High Energy Physics

In this lecture, I will briefly cover the classical or quantum neural tangent kernel theory from the vision of high energy theoretical physics. The topics include neural network introductions, neuron output and non-Gaussianity, perturbation theory and non-perturbative criticality, Haar integrals and quantum neural tangent kernel.  

Studying material: based on the book: [2106.10165] The Principles of Deep Learning Theory (arxiv.org) and the paper: [2111.04225] Representation Learning via Quantum Neural Tangent Kernels (arxiv.org)
 
17:00 to 17:30 Jun Nishimura (KEK, Japan) Infrared regularization of the Lorentzian IKKT matrix model and the emergence of expanding universe

The IKKT matrix model has been investigated as a nonperturbative formulation of superstring theory for more than two decades. Unlike the Euclidean version, the Lorentzian version is not well defined as it is since the partition function is not absolutely convergent. If we define the Lorentzian model by contour deformation that amounts to the Wick rotation, the model is essentially equivalent to the Euclidean model. In particular, this implies that we cannot obtain a real space-time with Lorentzian signature.
Here we propose to regularize the theory by introducing a Lorentz invariant mass term. By studying this model using the complex Langevin method to overcome the sign problem, we observe the emergence of a real space-time with Lorentzian signature. Moreover, we obtain an exponential expansion reminiscent of inflation. The Lorentz symmetry is spontaneously broken, but for the bosonic model, there is only one spatial direction that expands. We discuss a mechanism for the possible
emergence of three expanding directions in the presence of supersymmetry.
   
17:45 to 18:15 Anna Hasenfratz (University of Colorado, USA) 8 Fundamental Flavors and the sill of the Conformal Window
 
18:15 to 18:45 Yannick Meurice (University of Iowa, USA) Quantum Simulating Gauge Theories: from Tensor field theory to Rydberg Atom Simulators

We introduce tensor lattice field theory as a method to discretize the path-integral formulations of lattice models suitable for quantum computing. The individual tensors appear as the local building blocks of the reformulation. They contain all the information about the model and its symmetries. Using the transfer matrix formalism, we introduce the Hilbert space and truncations that respect the symmetries. We present a quantum Hamiltonian for scalar electrodynamics in one and two spatial dimensions where the electric field Hilbert space is approximated by a spin-1 triplet.  We discuss quantum simulators for this model obtained by assembling arrays of Rydberg atoms with  ladder structures and report on the recent experimental progress towards this implementation.
 
Wednesday, 31 August 2022
Time Speaker Title Resources
10:00 to 18:45 - Discussions
Thursday, 01 September 2022
Time Speaker Title Resources
10:00 to 11:15 Georg Bergner (University of Jena, Germany) Matrix Models, Gauge-Gravity Duality, and Simulations on the Lattice (Lecture 2)
 
11:45 to 13:00 Daisuke Kadoh (Doshisha University, Japan) An Introduction to Tensor Renormalization Group (Lecture 2)
 
14:30 to 15:00 Saumen Datta (TIFR, Mumbai, India) QCD in deconfined phase: Heavy quark as probe

I will discuss lattice results for the momentum diffusion coefficient of the heavy (charm and bottom) quarks in the QCD plasma.
   
15:00 to 15:30 Andreas Schaefer (University of Jena, Germany) Is there a Holographic Description of Heavy-Ion Collisions beyond the Page time?

AdS/CFT has been very succesful in describing qualitatively and sometimes even quantitatively the early phase of high-energy heavy-ion collisions (HICs). However, QCD processes have unitary time evolution, are time reversal invariant and thus cannot produce thermodynamic entropy. Therefore, the entropy in HICs should really show a page curve when followed to the final hadronic state. We discuss ideas for possible extensions of holographic descriptions which could model such a Page curve.
   
16:00 to 16:30 Sandip Trivedi (TIFR, Mumbai, India) Target Space Entanglement and Space-Time Geometry
   
16:30 to 17:00 Erez Zohar (Hebrew University, Israel) Quantum simulation of lattice gauge theories - requirements, challenges and methods

Over recent years, the relatively young field of quantum simulation of lattice gauge theories, aiming at implementing simulators of gauge theories with quantum platforms, has gone through a rapid development process. Nowadays, it is not only of interest to the quantum information and technology communities. It is also seen as a valid tool for tackling hard, non-perturbative gauge theory problems by particle and nuclear physicists. Along the theoretical progress, nowadays more and more experiments implementing such simulators are being reported, manifesting beautiful results. In my talk, I will review the essential ingredients and requirements of lattice gauge theories, discuss their meanings, the challenges they pose and how they could be tackled, potentially aiming at the next steps of this field.
 
 
17:00 to 17:30 Oscar Dias (University of Southampton, UK) New phases of N=4 SYM at finite chemical potential

We do a systematic search of supergravity solutions that, via the AdS5/CFT4 correspondence, are dual to thermal states in N=4 SYM at finite chemical potential. These solutions are required to ultimately reproduce the microscopic entropy of AdS black holes. Using a mix of analytical and numerical methods, we construct and study static and rotating charged hairy solitonic and black hole solutions with global AdS5 asymptotics. They are constructed in a consistent truncation of five dimensional SO(6) gauged supergravity and can thus be uplifted to asymptotically AdS5 x S5 solutions of type IIB supergravity (it is also a truncation of N=8 gauged supergravity). Hairy black holes exist above a critical electric charge and merge with the known Cvetic-Lu-Pope (CLP) black holes along a curve determined by the onset of superradiance in the latter family. The hairy black holes then extend all the way up to the BPS limit (in a phase diagram) and they dominant the microcanonical ensemble when they coexist with the CLP black holes. In the BPS limit, our finite temperature black holes approach new supersymmetric hairy black holes that reduce to the supersymmetric Lucietti-Kunduri-Reall black hole family when the hair condensate vanishes. Our findings permit a good understanding of the full phase space of SYM thermal states with three arbitrary chemical potentials and finite charged scalar fields.
 
17:45 to 18:15 Paul Romatschke (University of Colorado, USA) 3/4, 4/5 and 1/(4Pi)-- Towards Understanding Universal Ratios at Large N

 

The two holographic results that arguably had the biggest impact on experiments in nuclear physics are 3/4 and 1/(4 Pi), the ratios of strong to weak entropy density and shear viscosity to entropy density in N=4 SYM. Twenty years later, much progress has been
made in holography, but a simple understanding of these ratios is still lacking. In this talk, I will review a purely field theoretical approach to a different field theory, namely the O(N) vector model, which is solvable in the strong coupling limit at large N. Calculating the same ratios as in N=4 SYM, I find 4/5 and eta/s~0.42 N, respectively, and will attempt an interpretation of these findings.
 
18:15 to 18:45 Martin Kruczenski (Purdue University, USA) The S-matrix Bootstrap in 2d and 4 Primal and Dual Problem

First, I am going to describe bootstrap methods applied to the loop equation in Lattice QCD (pure YM theory). Second I am going to consider the S-matrix bootstrap applied to the computation of S-matrices in the 2d non-linear sigma model,  a toy model for QCD. Finally I am going to consider applications of the S-matrix bootstrap to meson scattering.

 
   
Friday, 02 September 2022
Time Speaker Title Resources
10:00 to 11:15 Georg Bergner (University of Jena, Germany) Matrix Models, Gauge-Gravity Duality, and Simulations on the Lattice (Lecture 3)
 
11:45 to 13:00 Daisuke Kadoh (Doshisha University, Japan) An Introduction to Tensor Renormalization Group (Lecture 3)
 
14:30 to 15:00 Georg Bergner (University of Jena, Germany) Matrix Models, Gauge-Gravity Duality, and Simulations on the Lattice (Lecture 4)
 
15:00 to 15:30 Zechuan Zheng (ENS Paris, France) Bootstrapping the lattice Yang-Mills theory

I will speak about my recent work with Vladimir Kazakov where we study the SU lattice YangMills theory in the planar limit at dimensions 234 via the numerical bootstrap method It combines the MakeenkoMigdal loop equations with the cutoff on the maximal length of loops and the positivity conditions on certain correlation matrices Our algorithm is inspired by the pioneering paper of P Anderson and M Kruczenski but it is significantly more efficient as it takes into account the symmetries of the lattice theory and uses the relaxation procedure in the line with our previous work on matrix bootstrap We thus obtain the rigorous upper and lower bounds on the plaquette average at various couplings and dimensions The results are quickly improving with the increase of cutoff For 4 and 16 the lower bound data appear to be close to the Monte Carlo data in the strong coupling phase and the upper bound data in the weak coupling phase reproduce well the 3loop perturbation theory We attempt to extract the information a bout the gluon condensate from this data Our results suggest that this bootstrap approach can provide a tangible alternative to so far uncontested the Monte Carlo approach.
 
16:00 to 16:30 Daisuke Kadoh (Doshisha University, Japan) An Introduction to Tensor Renormalization Group (Lecture 4)
 
16:30 to 17:00 Andy Stergiou (Kings College, UK) CFTs with U(m)xU(n) Global Symmetry in 3D and the Chiral Phase Transition of QCD

The chiral phase transition of QCD with 2 or 3 massless flavors has been the subject of numerous investigations over the years. The existence of 3D CFTs with U(m)xU(n) global symmetry may indicate a second order transition, specifically for the case m=n which is relevant for n-flavor massless QCD with effectively restored axial U(1) symmetry. U(m)xU(n) CFTs have been studied in the ε expansion below 4 dimensions, with the conclusion that 2- and 3-flavor massless QCD with effectively restored axial U(1) cannot have a second order chiral phase transition. After reviewing these results, I will present non-perturbative results of a numerical conformal bootstrap analysis of 3D CFTs with U(m)xU(n) global symmetry.
 
 
17:00 to 17:30 Judah Unmuth- Yockey (Fermi National Accelerator Laboratory, USA) Ising spin and gauge on hyperbolic lattices

The Ising spin model when simulated on a two-dimensional Euclidean hyperbolic lattice possesses spin-spin correlations on the boundary that are approximately power-law.  Similarly, Z2 gauge theory on a three-dimensional hyperbolic lattice possesses Wilson loops and plaquette-plaquette correlations with approximately power-law behavior.  We discuss the details of these observations and their origins.
   
17:30 to 17:45 Organizers Closing remarks