Triangle Seminars

Abstract:
We review large-N QCD from its inception to the most recent developments, organizing the subject into four ages.
— Prehistorical: From dual models and string theory to the discovery of deep inelastic scattering and the subsequent rise of QCD.
— Historical: The introduction of the large-N expansion for QCD by ’t Hooft.
— Modern: The “resurrection” of the string program through the emergence of gauge/gravity duality.
— Contemporary: The obstructions to the string program arising from QCD asymptotic freedom and the most recent advancements.

Abstract:
Our understanding of interacting CFTs in d>2 dimensions was revolutionized by modern developments in the analytical and numerical conformal bootstrap. The poster child of this program, the non-exactly solvable 3d Ising CFT, is now understood to an unprecedented level of detail. In contrast, our understanding of 2d CFTs encompasses large classes of exactly solvable models (the so-called rational CFTs), and a set of universal bootstrap results which apply only to "generic" non-exactly solvable CFTs of which no concrete example is available. In this talk, we summarize our recent attempts at constructing such theories by coupling exactly solvable CFTs and flowing to IR fixed points. We will discuss perturbative and non-perturbative constructions as well as some dual bounds on the set of conserved currents in the IR. 

Abstract:
Black-hole spectroscopy aims to infer physical properties of black holes by detecting the spectrum of quasi-normal modes (QNMs) they emit while settling towards equilibrium. Gravitational analogs aim to explore aspects of black hole systems by building laboratory experiments that share features of the black hole and its perturbations. A particularly interesting aspect of QNMs is the phenomenon of spectral instability: the complex frequencies of the modes wander as perturbations of the spacetime around the black hole are introduced. Having the ability to simulate in a controlled environment the behaviour of these modes is therefore appealing. I will describe the quantum vortex analog recently developed in the Nottingham Black Hole Laboratory and discuss the problem of how to identify the quasi-normal modes for such a confined system, as well as showing data from the experiment.

Abstract:
AI for Mathematical Sciences (AIMS) seminar series

In this talk, I will explain how to construct numerically several new unstable singularities to certain equations in fluids (CCF, IPM, Boussinesq) using machine learning methods. Our approach combines curated machine learning architectures and training schemes with a high-precision Gauss-Newton optimizer, achieving accuracies that significantly surpass previous work across all discovered solutions, reaching near double-float machine precision, attaining a level of accuracy constrained only by the round-off errors of the GPU hardware, potentially leading to rigorous mathematical validation via computer-assisted proofs.

To subscribe for the AIMS series please fill out the form https://applications.lims.ac.uk/subscribe-to-aims

Abstract:
Perturbative calculations of string amplitudes are twofold: an expansion in the string coupling (the genus expansion of the worldsheet) and a low-energy expansion in the momenta. In this talk, I will focus on the low-energy expansion of closed string amplitudes at genus one, specifically for four- and five-point massless states of type IIB superstrings in flat spacetime. Evaluating these amplitudes involves integrating over the moduli space of punctured tori. I will demonstrate how the formalism of equivariant iterated Eisenstein integrals can be used to systematically calculate these integrals. Additionally, I will discuss the implications of these results for the S-duality of type IIB.