Junggi Yoon (APCTP)
Time: 10:30~11:30
Title: Emergent factorization of Hilbert space at large $N$ and black hole
Abstract: In this talk, we discuss the emergent factorization of Hilbert space in low-energy description of matrix models and its implications for the black hole information paradox. First, I will explain the motivation of our works based on the black hole information paradox. Then, I will present the collective description of the low-energy sector of matrix model. Based on this toy model, I will give comments on the recent progresses in the black hole information paradox: black hole complementarity, island conjecture and holography of information.
Suro Kim (KIAS)
Time: 13:30~14:30
Title: Constraining millicharged dark matter with gravitational positivity bound
Abstract: Positivity bound is one of the UV-IR consistency conditions from fundamental principles
such as unitarity and causality, and it gives useful constraints on phenomenological models. In this talk, we study the implications of the gravitational positivity bound for dark matter. In particular, we focus on the millicharged dark matter and constrain their parameter spaces.
Myeonghun Park (SeoulTech)
Time: 14:30~15:30
Title: Calculating scattering amplitudes with ML and QC
Abstract: As the energy of collision in colliders is increasing more than O(10) TeV, we need to consider how to calculate scattering amplitudes with large multiplicities more precisely. In this talk, I will introduce various methods to calculate scattering amplitudes with Machine Learning and Quantum Computing algorithms.
Euihun Joung (Kyung Hee University)
Time: 16:00~17:00
Title: Spinor-helicity representations of (A)dS4 particles of any mass
Abstract: We construct the spinor-helicity representations of massive and (partially-)massless particles in four dimensional (Anti-) de Sitter spacetime using the framework of the dual pair correspondence. We show that the dual groups (aka "little groups") of the AdS and dS groups are respectively O(2N) and O*(2N). For N=1, the generator of the dual algebra corresponds to the helicity operator, and the spinor-helicity representation describes massless particles in (A)dS4. For N=2, the dual algebra is composed of two ideals which fixes the spin and the mass of the particle, respectively. In the case of a positive cosmological constant, namely dS4, the spinor-helicity representation contains all massive particles corresponding to the principal series representations and the partially-massless particles corresponding to the discrete series representations leaving out only the light massive particles corresponding to the complementary series representations. Finally, we consider the multilinear form of helicity spinors invariant under (A)dS group, which can be served for the (A)dS counterpart of the scattering amplitude.
Hojin Lee (Seoul National University)
Time: 10:00~11:00
Title: Quantum Perturbiner Method and Optical Theorem
Abstract: The optical theorem, which reveals the relationship between cross sections and the discontinuities of the scattering amplitudes, can be achieved by applying Cutkosky's rule on each Feynman diagram. In this talk, I will present an alternative way called the Quantum Perturbiner Method. Quantum Perturbiner method is a method that one can derive scattering amplitudes recursively for a given action, without any need to suffer from Feynman rules or diagrams. During the talk, I will show how Quantum Perturbiner Method can be extended to cross sections and opitcal theorem.
Sangmin Lee (Seoul National University)
Time: 11:00~12:00
Title: Massive twistor particles in electromagnetic fields
Abstract: We study the (ambi-)twistor model for spinning particles interacting via electromagnetic field, as a toy model for studying classical dynamics of gravitating bodies including effects of both spins to all orders. The all-orders-in-spin effects are encoded as a dynamical implementation of the Newman-Janis shift. We confirm that the classical eikonal can be understood as the generator of canonical transformations that map the in-states of a scattering process to the out-states, entailing all-orders-in-spin dynamics up to at least one-loop order.
Kanghoon Lee (APCTP)
Time: 13:30~14:30
Title: The Schwarzschild Black Hole from Perturbation Theory to All Orders
Abstract: Applying the quantum field theoretic perturbiner approach to Einstein gravity, we compute the metric of a Schwarzschild black hole order by order in perturbation theory. Using recursion, this perturbative calculation can be carried out in de Donder gauge to all orders in Newton’s constant. The result is a geometric series which is convergent outside a disk of finite radius, and it agrees within its region of convergence with the known de Donder gauge metric of a Schwarzschild black hole. It thus provides a first all-order perturbative computation in Einstein gravity with a matter source, and this series converges to the known non-perturbative expression in the expected range of convergence.
Gungwon Kang (Chung-Ang University, Korea)
Time: 14:30~15:30
Title: Non-merging ringdown radiations in close black hole encounters
Abstract: We have numerically investigated close scattering processes of two black holes (BHs). Our careful analysis shows for the first time a non-merging ringdown gravitational wave induced by dynamical tidal deformations of individual BHs during their close encounter. The ringdown wave frequencies turn out to agree well with the quasi-normal ones of a single BH in perturbation theory, despite its distinctive physical context from the merging case. Our study shows a new type of gravitational waveforms and opens up a new exploration of strong gravitational interactions using BH encounters. [arXiv: 2310.18686]
Changhyun Ahn (Kyungpook National University)
Time: 16:00~17:00
Title: On Celestial Holography
Abstract: A quantum gravity is an outstanding open problem in the current modern physics. The complete theory of quantum gravity would provide the microscopic structure underlying systems whose long distance behavior is described by the general relativity of Einstein’s theory. Celestial holography studied during last ten years provides a new approach to quantum gravity in four dimensional asymptotically flat spacetimes by searching for its holographic correspondence. Celestial holography proposes a duality between gravitational scattering in four dimensional asymptotically flat spacetimes and a conformal field theory living on the two dimensional celestial sphere. I will present 1) Introduction, 2) Infrared structure of gravity, 3) From four dimensional gravity to two dimensional celestial conformal field theory, 4) Celestial amplitudes and celestial OPEs, 5) Soft symmetries, 6) My recent works, and 7) Open problems. This will provide the way to observe directly (or indirectly) the evidence of superstring (or M) theory in our real world.