Week 28.11.2021 – 04.12.2021

After reviewing the role Quasi-Normal Modes (QNMs) play in the Gravitational Wave (GW) signals emitted in the ring-down phase of Black-Hole (BH) mergers, we present a novel efficient approach to compute QNMs of BHs, D-branes and fuzz-balls, based on quantum Seiberg-Witten (SW) curves for N=2 supersymmetric Yang-Mills (SYM) theories. We find remarkable agreement with numerical results obtained by means of Leaver's method of continuous fractions and with `semi-classical' results obtained in the eikonal approximation, based on geodetic motion. Finally we discuss the extension to D3-branes and their bound states of Couch-Torrence (CT) conformal inversions, that exchange horizon and infinity, and show that they keep the photon-sphere (or photon-halo) fixed.

To many people, the phrase “the theory of everything” conjures memories of the Oscar-winning film about the life and science of Prof. Stephen Hawking. Yet the quest referred to in that title goes back much further. It is nothing less than the search for the holy grail of science: an elegant unified theory, encompassing all matter, forces and space-time itself. It stretches from Galileo and Newton, via Einstein and Dirac, to the most recent advances in superstring theory. In this event, Prof. Yang-Hui He presents the story as a dance of discovery between data, physics and mathematics, each anticipating the other’s moves. They have all taken the lead at different times, yet for many today, including Prof. He, the guiding principle is the rigour and beauty of mathematics. It is fitting that this event is held at the Royal Institution, where Faraday uncovered the principles of electromagnetism. These inspired Maxwell's equations, a key component of any unifying theory.

Following the recent work of Eberhardt, Gaberdiel and Gopakumar, exact comparison between various quantities living on the two sides of the AdS/CFT duality has become a possibility. The goal of this talk will be to extend the existing holographic dictionary to include some non-perturbative vacua on both sides. I will start by reviewing the original, purely closed-string setup, giving arguments that string theory on AdS3 x S3 x T4 with minimal k=1 NS-NS flux is exactly dual to the symmetric-product orbifold CFT with the T4 as the seed. I will then construct various D-branes of this string theory and calculate their associated cylinder amplitudes. We will observe that these amplitudes match with the cylinder correlators of certain boundary states of the dual CFT, thus suggesting a direct correspondence between these boundary conditions. I will also show that the disk amplitudes of these D-branes localise to those points in the worldsheet moduli space where the worldsheet disk holomorphically covers the spacetime disk. This talk is based on https://arxiv.org/abs/2110.05509. ---- Part of the London Integrability Journal Club. Please register at integrability-london.weebly.com if you are a new participant. The link will be emailed on Tuesday.