Triangle Seminars

Abstract:
Models of random matrices can be viewed as zero-dimensional analogs of usual field theory. Despite decades of exploration, matrix models remain at the forefront of intensive research, motivated by a rich web of connections to string theory, quantum gravity, integrability, Yang-Mills theory, combinatorics, geometry and representation theory. These lectures will present a pedagogical introduction to the subject.

​Lecture 1. Motivation and basic definitions. Hermitian matrix models: Feynman rules, ribbon graphs, large N genus expansion.

Abstract:
We devise a formalism to probe local physics about a bulk point in general geometries using boundary correlators. In the exterior region, this allows for the factorization of boundary correlators in terms of flat-space like scattering amplitudes. The formalism also leads to direct measurements using lightcones emerging from the bulk point, capturing the boundary imprint of bulk causality.

Next, we use it to understand the physics of the black hole interior using the past lightcone, where we generalize known relations involving two-point correlators to spectral density tails and to four-point correlators. Details about the interior tunnel to the exterior at the cost of a Boltzmann suppression exp(-1/(2Tx)), where x is the desired spatial resolution. We comment on the relation (or lack thereof) between such measurements and the experience of infalling observers.

Abstract:
Stage IV Large Scale Structure Surveys are ushering in a new
era of precision cosmology! In this talk, I will explore the effort to test gravity on cosmological
scales, highlighting the theoretical advancements aimed at constructing
an optimal framework. I will also touch on the synergy with
gravitational wave surveys. Additionally, I will provide a detailed
review of recent findings based on currently available data and conclude
with an outlook on the challenges and future prospects in this field.

Abstract:
See https://www.newton.ac.uk/seminar/49000/
Date 22 October 2025 – 13:15 to 14:45
Venue INI Seminar Room 2

Weak Parity Violation means that the the weak force in the Standard Model exhibits maximal parity violation, coupling exclusively to left-handed fermions. In contrast, the Strong CP Problem asks why strong force appears to preserve CP symmetry so precisely—namely, why the effective QCD θ-angle is zero or extremely small. In this talk, I will discuss how these two long-standing puzzles in the weak and strong sectors may be intimately connected and resolved through Symmetric Mass Generation (SMG) — a novel mechanism by which matters acquire mass without spontaneous symmetry breaking, within an anomaly-free symmetry framework. I will illustrate the idea using a set of toy models, possibly formulated in dimensions other than 4, that capture the essential features of this proposed resolution. References therein: arXiv 2204.14271, 2207.14813, 2212.14036.

Abstract:
Solutions to general relativity with a negative cosmological constant have received significant attention due to the conjectured AdS/CFT correspondence, a particularly well-understood example of which is exhibited in 2+1 dimensions. I will review known vacuum solutions to general relativity with a negative cosmological constant in 2+1 dimensions and discuss the difficulties in defining mass, which are resolved via minimisation using a positive energy theorem. I will present a gluing theorem for vacuum time-symmetric general-relativistic initial data sets in two spatial dimensions. By gluing two given time-symmetric vacuum initial data sets at conformal infinity, we obtain new time-symmetric vacuum initial data sets. I will sketch the derivation of the mass formulae of the resulting manifolds. Our gluing theorem yields complete manifolds with any mass aspect function, which are smooth except for one conical singularity.