Fri, 15 May 2026
11:00 -
12:00
L2
Prelims Preparation
Abstract
This session is aimed at first-year undergraduates preparing for Prelims exams. A panel of lecturers and current students will share key advice on exam technique and revision strategies, offering practical tips from their own experience.
Mon, 25 May 2026
15:30 -
16:30
L2
Tue, 28 Apr 2026
13:00
13:00
L2
Schwinger-Keldysh hydrodynamics of the SYK lattice
Akash Jain
(Oxford )
Abstract
Hydrodynamics provides a universal low-energy effective description of interacting many-body systems. Traditionally, it is formulated in terms of equations of motion derived from the relevant conservation laws. However, this classical framework neglects fluctuations of hydrodynamic observables required by the fluctuation–dissipation theorem (FDT). The Schwinger–Keldysh effective field theory (SK EFT) offers a Wilsonian, action-based formulation of hydrodynamics that systematically incorporates such fluctuations. In this approach, the effective action is generically non-unitary (complex), encoding macroscopic dissipation, while the FDT is implemented through a discrete Kubo–Martin–Schwinger (KMS) symmetry. This symmetry also underlies the emergence of the second law of thermodynamics within hydrodynamics.
In this talk, we will discuss the first-ever derivation of an SK EFT directly from a local, unitary microscopic Hamiltonian. Specifically, we will consider a one-dimensional chain of SYK dots with Gaussian-random interactions between nearest neighbours. This system possesses a single conserved quantity—energy—and accordingly its low-energy dynamics are governed by an SK EFT for energy diffusion. We will identify the fundamental and emergent symmetries of this theory and derive the associated classical entropy current for SYK chains. Time permitting, we will also comment on applications to out-of-time-ordered correlators of energy fluctuations. The talk will be based on the recent paper with Marta, Mark, and Alexey: https://arxiv.org/pdf/2604.18675.
Tue, 10 Mar 2026
13:00
13:00
L2
Hodge Structures of Complex Multiplication Type from Rational Conformal Field Theories
Pyry Kuusela,
(Sheffield)
Abstract
Gukov and Vafa have proposed that a conformal field theory describing a string compactification on a manifold is rational (an RCFT) if and only if the manifold admits complex multiplication (CM). We investigate and extend the Gukov-Vafa proposal by constructing Hodge structures of CM type using only RCFT data, without reference to a geometric interpretation.
We use the chiral and boundary states of the RCFT to construct the complex and rational vector spaces underlying the Hodge structure. Using the known notion of Galois symmetry of RCFTs and some elementary Galois theory, we are able to show that these Hodge structures are of CM-type, subject to some technical assumptions that can be verified explicitly for large classes of theories, including those without known geometric interpretation. We also discuss briefly the relation of complex multiplication to arithmetic geometry.
This talk is based on arXiv:2510.25708 with H. Jockers and M. Sarve.
Tue, 05 May 2026
13:00
13:00
L2
The Bootstrap Siege of M-theory
Andrea Guerrieri
(City University )
Abstract
In recent years, analytic and numerical Bootstrap methods have emerged as powerful tools to probe non-perturbative aspects of quantum field theory and quantum gravity. In this talk I will discuss the nonperturbative S-matrix Bootstrap approach to scattering amplitudes in maximal supergravity. After a brief overview of the method, I will review earlier results obtained in this framework, including bounds on the Wilson coefficient of the R^4 operator in D=9,10,11, and the observation that string and M-theory amplitudes appear to lie on the boundary of the allowed bootstrap region. I will then present preliminary results for the higher dimensional corrections like the D^4 R^4 interaction in eleven dimensions and show how the resulting constraints on the non-perturbative M-theory scattering amplitude match expectations from string/M-theory.
Mon, 15 Jun 2026
16:30 -
17:30
L2
TBA
Prof. Jinchao Xu
(King Abdullah University of Science and Technology (KAUST))
Abstract
TBA
This is a joint OxPDE and Numerical Analysis seminar.
Tue, 03 Mar 2026
13:00
13:00
L2
Beyond Wigner - How Non-Invertible Symmetries Preserve Probabilities
Thomas Bartsch
(Oxford )
Abstract
Recent years have seen the expansion of the traditional notion of symmetry in quantum theory to so-called generalised or categorical symmetries, which may in particular be non-invertible. This seems to be at odds with Wigner's theorem, which asserts that quantum symmetries ought to be implemented by (anti)unitary -- and hence invertible -- operators on the Hilbert space. In this talk, we will try to resolve this puzzle for generalised symmetries that are described by (higher) fusion categories. After giving a gentle introduction to the latter, we will discuss how one can associate an inner-product-preserving operator to (possibly non-invertible) symmetry defects and illustrate our construction through concrete examples. Based on the recent work 2602.07110 with Gai and Schäfer-Nameki.