报告题目： The photon sphere and response functions in AdS/CFT
报 告 人: 孙昊宇，University of Texas at Austin
邀 请 人 ：周思益
时 间： 2024年1月26号（星期五）15:00
地 点： 腾讯会议：545-826-527
Abstract: We demonstrate that the photon sphere plays a surprising role in the holography for small AdS-Schwarzschild black holes. A precise formula is derived to show how a black hole amplifies or attenuates an oscillating source dual to boundary operators across the bulk. We estimate the quasi-normal modes of small black holes at large angular momenta $l$. The lowest mode matches the phase transition for the massless scalar fields and the null geodesics, which are identified with the short-lived excitations of the black hole at large $l$. This sharpens the conjecture by Hashimoto that the photon sphere seen by a boundary observer is the spatial Fourier transform of the response function. The conjecture agrees excellently with numerics after certain long-lived excitations -- associated with geodesics connecting boundary points, predicted by Festuccia and Liu -- are removed from the response, which is then controlled by the short-lived excitations of the black hole.
Brief CV:
Haoyu Sun received his bachelor degrees in physics, math, and microbial biology from in 2014, and PhD in physics in 2020, both from UC Berkeley. He is now a postdoc at UT Austin, associated with the Ultra-Quantum Matter Simons Collaboration. He will move to Georgia Tech as a research scientist this fall. His main interests lie in string theory, holography, and their intersections with geometric topology and condensed matter physics.
