34th Chris Engelbrecht Summer School & 8th Mandelstam Theoretical Physics (MITP) School and Workshop on 'Large N and the Emergence of Holography'

8 Jan 2026, 09:00 → 14 Jan 2026, 21:20 Africa/Johannesburg

Seminar Room (NITheCS, Merensky Building,Stellenbosch University)

This joint event brings together two prestigious programmes in theoretical physics, offering five days of lectures, tutorials, and research discussions. International plenary lecturers will each present two pedagogical talks aimed at graduate students and one technical talk during the School. The Workshop will feature cutting-edge research presentations by both local and international participants.

The format of the event encourages lively discussion, promotes collaboration, and drives the exploration of new research directions in theoretical high energy physics.

The theme is "Large N and the Emergence of Holography”.

 

Who should attend?

• Postgraduate students
• Early-career researchers
• Academics

 

 Pedagogical Lecturers

• Tarek Anous (Queen Mary University of London, UK)
• Lorenzo di Pietro (Trieste University)
• Seok Kim (Seoul National University, Korea)
• Costis Papageorgakis (Queen Mary University of London, UK)
• Xinan Zhou (Shanghai Technical University and Kavli Institute for Theoretical Sciences, China)

 

CLICK TO REGISTER TO ATTEND ONLINE

More about the event

Organisers

• Pallab Basu (University of the Witwatersrand)
• Robert de Mello Koch (Huzhou University, China)
• Kevin Goldstein (University of the Witwatersrand)
• Vishnu Jejjala (University of the Witwatersrand)
• Antal Jevicki (Brown University, USA)
• Anosh Joseph (University of the Witwatersrand)
• João Rodrigues (University of the Witwatersrand)
• Sam van Leuven (University of the Witwatersrand)

 

Local Participants (South Africa)

• Victoria Adeleke (Mangosuthu University of Technology)
• Pallab Basu (University of the Witwatersrand)
• Jarryd Bath (University of Pretoria)
• Immanuel Booysens (University of Pretoria)
• Warren Carlson (University of the Witwatersrand)
• Kevin Goldstein (University of the Witwatersrand)
• Siyanda Hlathi (University of KwaZulu-Natal)
• Anosh Joseph (University of the Witwatersrand)
• Simon Kahn Tollman (University of the Witwatersrand)
• Eleanor Kedem (Stellenbosch University)
• Garreth Kemp (University of Johannesburg)
• Thabo Lepota (University of the Witwatersrand)
• Bigboy Madlala (University of the Witwatersrand)
• Vinod Mamale (University of the Witwatersrand)
• Lehlogonolo Mashigo (University of Pretoria)
• Kayleigh Mathieson (University of the Witwatersrand)
• Bradley Mkhondo (University of the Witwatersrand)
• Kutloano Nkojoana (University of the Witwatersrand)
• Caleb Nyathi (University of Cape Town)
• Nicholas Pather (University of Cape Town)
• João Rodrigues (University of the Witwatersrand)
• Abinash Swain (University of the Witwatersrand)
• Laila Tribelhorn (University of Pretoria)
• Sam van Leuven (University of the Witwatersrand)
• Khadija Windo (University of South Africa)
• Konstantinos Zoubos (University of Pretoria)

 

International Participants

• Tarek Anous (Queen Mary University London, UK)
• Antal Jevicki (Brown University, USA)
• Seok Kim (Seoul National University, South Korea)
• Vamika Longia (Indian Institute of Science Education and Research Mohali, India)
• Costis Papageorgakis (Queen Mary University London, UK)
• Lorenzo Di Pietro (Trieste University, Italy)
• Robert de Mello Koch (Huzhou University, China)
• Xinan Zhou (Shanghai Technical University, China)

 

About Chris Engelbrecht

Chris Engelbrecht was a renowned South African theoretical physicist, teacher, and mentor whose legacy continues through this long-running annual programme. The Chris Engelbrecht Summer School, organised under the auspices of NITheCS, provides advanced training in theoretical physics.

 

About Stanley Mandelstam

Stanley Mandelstam was an eminent South African-born American theoretical physicist and Wits University graduate, recognised for his pioneering contributions to particle physics and string theory. The Mandelstam Theoretical Physics School and Workshop is named in his honour to continue his legacy of advancing fundamental physics.

 

Acknowledgements

The organisers gratefully acknowledge NITheCS for its generous funding of the School and Wits University for its valued support.

 

CLICK TO REGISTER TO ATTEND ONLINE

34th Chris Engelbrecht Summer School.pdf

Mandelstam8_34CE_schedule.pdf

Thursday 8 January

09:00 Coffee/Tea

1 Welcome

2 QFT in AdS: Kinematics - Lorenzo Di Pietro (Trieste University, Italy)

AdS geometry: bulk and boundary; Isometry constraints on correlation functions; Bulk state / Boundary operator correspondence; Boundary operator product expansion.

Speaker: Lorenzo Di Pietro (Trieste University, Italy)

10:30 Coffee/Tea

3 Hairy black holes in AdS - Seok Kim (Seoul National University, China)

I will talk about the black hole instabilities in AdS and the new hairy black hole configurations which we suggest to be the endpoints. Based on these findings, I will suggest better pictures on the spectral/entropic structures of the AdS quantum gravity.

Speaker: Seok Kim (Seoul National University, China)

4 Diagonalization as RG - Pallab Basu (University of the Witwatersrand, South Africa)

We investigate large-N spin models that parallel the Sachdev–Ye–Kitaev construction and provide a controlled setting for studying manybody chaos. By implementing a Pandey–Mehta–type large-N crossover, we interpolate between distinct random-matrix universality classes and track how spectral correlations evolve with the crossover parameter. Using the adjacent-level spacing r-ratio and Krylov complexity as complementary probes of static and dynamical chaos, we demonstrate a clear progression from weakly correlated spectra to fully developed quantum scrambling.

Speaker: Pallab Basu (University of the Witwatersrand, South Africa)

12:30 Lunch/Discussions

5 Finiteness of Hilbert Space in Bi-Local Holography - Antal Jevicki (Brown University, USA)

Vector field theories, dual to Higher Spin gravity are considered at Finite N. In the collective field representation a reduction of Hilbert space is discussed with implications on finiteness of the Trace and Entropy in this holographic representation.

Speaker: Antal Jevicki (Brown University, USA)

15:00 Coffee/Tea

6 Large N Master Field Optimization for Multi-Matrix Systems - Joao Rodrigues (University of the Witwatersrand, South Africa)

It is shown how large N properties of multi-matrix systems can be obtained by minimization of a loop truncated effective Hamiltonian expressed directly in terms of gauge invariant operators. The large N loop space constraints are handled by the use of master variables. For two and three massless Yang-Mills coupled matrices, highly accurate results for large N planar correlators, as well as spectrum, are presented. Generalization to larger number of matrices, relevant for systems such as BFSS, are discussed.

Speaker: Joao Rodrigues (University of the Witwatersrand, South Africa)

16:15 Free Time/Discussions

Friday 9 January

09:00 Coffee/Tea

7 QFT in AdS: Dynamics - Lorenzo Di Pietro (Trieste University, Italy)

OPE decomposition of bulk 2 pt functions and boundary 4pt functions; Example of the free scalar; Example of the O(N) model: various phases and their boundary interpretation.

Speaker: Lorenzo Di Pietro (Trieste University, Italy)

10:30 Coffee/Tea

8 Black hole microstates from cohomologies and their applications - Seok Kim (Seoul National University, China)

I will explain the cohomology program for the BPS black hole states in AdS/CFT. After explaining its general structures and examples, I will explain how to better understand the hairy BPS black hole states in this setup.

Speaker: Seok Kim (Seoul National University, China)

9 Spin chains for general N=2 quivers - Konstantinos Zoubos (University of Pretoria, South Africa)

The mapping of the dilatation operator of planar N=4 SYM to an integrable spin chain has led to tremendous progress in understanding the spectrum of the theory, both perturbative and non-perturbative. Gauge theories will less supersymmetry have received less attention. In this talk I will review recent progress in understanding the spin chains for planar N=2 superconformal theories obtained by orbifolding N=4 SYM and then marginally deforming. Although these spin chains have not been shown to be integrable, they still have more structure than one would naively expect.
I will discuss a range of techniques, including the Bethe ansatz and the superconformal index, which can be used to extract relevant information about the spectrum of these theories.

Speaker: Konstantinos Zoubos (University of Pretoria, South Africa)

12:30 Lunch/Discussions

10 Holography, bootstrap and defects - Xinan Zhou (Shanghai Technical University, KITP - UCAS, China)

In this series of lectures (and seminar) I will cover the following:
- The basics of perturbation theory in AdS and how bootstrap ideas can be used to efficiently compute holographic correlators. The example of 4d N=4 SYM in the dual supergravity limit will be analyzed in detail.
- How the bootstrap approach can be extended to include holographic defects. In particular, I will present the recent progress on giant graviton correlators.

Speaker: Xinan Zhou (Shanghai Technical University, KITP - UCAS, China)

15:00 Coffee/Tea

11 The AdS perspective on Confinement - Lorenzo Di Pietro (Trieste University, Italy)

I will discuss four dimensional non-abelian gauge theories in the background of Anti-de Sitter space. I will review how, imposing a Dirichlet boundary condition at small radius, there is a deconfinement/confinement transition as the radius is increased, while imposing a Neumann boundary condition a continuous extrapolation to the flat space limit is expected. I will then review recent investigations of this setup using both perturbation theory and nonperturbative methods.

Speaker: Lorenzo Di Pietro (Trieste University, Italy)

16:15 Free Time/Discussions

Monday 12 January

09:00 Coffee/Tea

12 The Conformal Bootstrap at Zero Temperature - Costis Papageorgakis (Queen Mary University London, UK)

I will introduce conformal field theories and the constraints imposed by conformal symmetry on correlation functions. After discussing primary operators, the operator product expansion, and conformal blocks, I will present the crossing equation for four-point functions. I will explain how unitarity - which guarantees positivity of OPE coefficients squared - enables the linear functional method to extract rigorous, non-perturbative bounds on CFT data.

Speaker: Costis Papageorgakis (Queen Mary University London, UK)

10:30 Coffee/Tea

13 BPS phases and fortuity in ABJ higher spin holography - Seok Kim (Seoul National University, China)

I will explain the large N BPS phases of the ABJ vector Chern-Simons model dual to a higher spin gravity, from the saddle points of its index. Their physical aspects are discussed from the viewpoint of trace relations and fortuitous operators. I will compare them with the AdS string theory and its black holes.

Speaker: Seok Kim (Seoul National University, China)

14 Configurational Temperature Diagnostics for Lattice Gauge Theories - Vamika Longia (IISER Mohali, India)

Built from the gradient and Hessian of the Euclidean action, a new temperature estimator for lattice gauge theories is being introduced. Drawing from geometric statistical methods, the estimator offers a gauge-invariant and momentum-free tool for checking thermodynamic consistency in Monte Carlo simulations. Rather than adjusting temperature indirectly through lattice size or coupling, this estimator pulls an effective temperature directly from field configurations. This allows for an independent evaluation of thermalization and sampling accuracy. In this work, the estimator is used with compact U(1) lattice gauge theories in one, two, and four dimensions. The measured temperatures are compared to input values across a wide range of couplings and lattice sizes. The method consistently produces target temperatures and is reliable against discretization effects and algorithmic artifacts. The estimator also acts as a tool to identify sampling defects, slow thermalization, and implementation errors in large-scale simulations. Future possibilities include extensions for non-Abelian gauge theories, anisotropic lattices, and inclusion in hybrid Monte Carlo workflows.

Speaker: Vamika Longia (IISER Mohali, India)

12:30 Lunch/Discussions

15 QFT in dS: The basics - Tarek Anous (Queen Mary University London, UK)

In this lecture we will introduce basic facts about QFT in de Sitter, highlighting the main differences with its flat-space counterpart. We will start by discussing the geometry of dS, its isometries, and the admissible particle representations. We will also discuss the maximally analytic vacuum of any interacting QFT: the Bunch Davies state.

Speaker: Tarek Anous (Queen Mary University London, UK)

15:00 Coffee/Tea

16 Finite Temperature CFT and Neural Networks - Costis Papageorgakis (Queen Mary University London, UK)

I will introduce CFTs at finite temperature, where the KMS condition replaces crossing symmetry as the central consistency constraint. Unlike at zero temperature, thermal OPE coefficients can have either sign, invalidating the linear functional approach. I will discuss neural networks as universal function approximators and explain how physics-informed neural networks (PINNs) can enforce the KMS condition directly. This sets the stage for the deep bootstrap framework presented in the main seminar.

Speaker: Costis Papageorgakis (Queen Mary University London, UK)

16:15 Free Time/Discussions

Tuesday 13 January

09:00 Coffee/Tea

17 Deep Finite Temperature Bootstrap - Costis Papageorgakis (Queen Mary University London, UK)

We introduce a novel method to bootstrap crossing equations in Conformal Field Theory and apply it to finite temperature theories on S1×Rd−1. Traditional bootstrap approaches relying on positivity constraints or truncation schemes are not applicable to this problem. Instead, we capture infinite towers of operators using suitable tail functions, which are bootstrapped numerically together with explicit CFT data. Our method employs three key ingredients: the Kubo-Martin-Schwinger (KMS) condition, thermal dispersion relations, and Neural Networks that model spin-dependent tail functions. We test the method on Generalized Free Fields and apply it to bootstrap double-twist thermal data in holographic CFTs.

Speaker: Costis Papageorgakis (Queen Mary University London, UK)

10:30 Coffee/Tea

18 Secondary Invariants, trace relations and fermions - Robert de Mello Koch (HuZhou University, China)

In this talk we describe the secondary invariants in bosonic vector models by employing a duality between bosonic and fermionic vector models. In this picture the set of bosonic secondary invariants are mapped, one-to-one, to the states of a fermionic bilinear color-singlet Hilbert space. We describe how the trace relations in the two descriptions are related.

Speaker: Robert de Mello Koch (HuZhou University, China)

19 Residue sums for superconformal indices - Sam van Leuven (University of the Witwatersrand, South Africa)

In this talk, I will present a method to evaluate superconformal indices of four-dimensional N=1 superconformal field theories in closed form. For the (1/8 BPS) Macdonald index of the N=4 SU(2) super Yang-Mills theory, the resulting expression manifests features of the BPS spectrum at non-zero Yang-Mills coupling. I will argue that the expression suggests the absence of “fortuitous” or non-graviton operators in this sector, which have been recently proposed as dual operators to (supersymmetric) black hole microstates in AdS5. If time permits, I will also discuss closed form expressions for the index in a simple subsector of the 1/16 BPS sector of the N=4 SU(N) theory for low values of N. For these cases, we are able to subtract off the “graviton index” from the full index, thus obtaining a closed form expression for the non-graviton index. The resulting expression reveals structural features of the non-graviton spectrum in this sector.

Speaker: Sam van Leuven (University of the Witwatersrand, South Africa)

12:30 Lunch/Discussions

20 Holography, bootstrap and defects - Xinan Zhou (Shanghai Technical University, KITP - UCAS, China)

In this series of lectures (and seminar) I will cover the following:
- The basics of perturbation theory in AdS and how bootstrap ideas can be used to efficiently compute holographic correlators. The example of 4d N=4 SYM in the dual supergravity limit will be analyzed in detail.
- How the bootstrap approach can be extended to include holographic defects. In particular, I will present the recent progress on giant graviton correlators.

Speaker: Xinan Zhou (Shanghai Technical University, KITP - UCAS, China)

15:00 Coffee/Tea

21 QFT in dS: The Issues - Tarek Anous (Queen Mary University London, UK)

The focus of this lecture will be on the various issues that arise when working with interacting QFTs on de Sitter using perturbation theory. Time permitting, we will also discuss the Euclidean approach to de Sitter QFT.

Speaker: Tarek Anous (Queen Mary University London, UK)

16:15 Free Time/Discussions

Wednesday 14 January

09:00 Coffee/Tea

22 Holography, bootstrap and defects - Xinan Zhou (Shanghai Technical University, KITP - UCAS, China)

In this series of lectures (and seminar) I will cover the following:
- The basics of perturbation theory in AdS and how bootstrap ideas can be used to efficiently compute holographic correlators. The example of 4d N=4 SYM in the dual supergravity limit will be analyzed in detail.
- How the bootstrap approach can be extended to include holographic defects. In particular, I will present the recent progress on giant graviton correlators.

Speaker: Xinan Zhou (Shanghai Technical University, KITP - UCAS, China)

10:30 Coffee/Tea

23 The case for integrability in dS - Tarek Anous (Queen Mary University London, UK)

QFT in dS: The Issues

In this lecture we will present what can be learned from exactly solvable models on de Sitter, working through examples.

Speaker: Tarek Anous (Queen Mary University London, UK)

24 Spread complexity in tensor product systems - Jaco van Zyl (University of Cape Town, South Africa)

Spread complexity can be solved for analytically in the case of simple Hamiltonians (i.e. Hamiltonians that are elements of some rank 1 algebra). For general Hamiltonians the Lanczos algorithm provides an algorithmic way to compute the Krylov basis and thus the spread complexity. A natural question to ask is what happens when one considers a Hamiltonian that is formed from a direct sum of subsystems for which the Krylov bases are known. In this talk I will discuss some general results that hold for such systems and under what conditions they simplify.

Speaker: Jaco van Zyl (University of Cape Town, South Africa)

12:30 Lunch/Discussions

14:00 Free Time/ Discussions

17:00 Dinner