Events

Date: 29 September 2026   Time: 14:00 - 15:30     

Location: MB503

NOTE: Pre talk intro for non experts starts at 2pm, with seminar starting at 2.30pm

Title: OPE = QNM: Analytic Structure, Black Holes, and Thermal Response

Abstract: Thermal correlators admit two complementary descriptions. At short times they are controlled by local operator data through the thermal OPE, while at late times they are governed by collective excitations, or quasinormal modes. Underlying these two descriptions is a richer analytic structure: the continuation of thermal correlators to complex time can encode information about bulk causal structure and the black-hole interior through complex-time singularities. We show that the thermal OPE and the quasinormal-mode expansion overlap in a common domain of complex time and therefore constrain one another through analyticity. This relation can be used constructively in both directions. Starting from OPE data, we recover low-lying quasinormal modes by analytic continuation and determine large-overtone frequencies and residues from the singularity structure of the correlator. In Mellin space, the relation becomes a set of spectral sum rules connecting the OPE spectrum to QNM data and constraining the allowed spectral structure. I will illustrate these ideas for holographic thermal correlators, in particular scalar perturbations of the Schwarzschild-AdS_5 black brane. More broadly, this suggests a bootstrap perspective on real-time thermal response in which microscopic operator data, causality, collective spectra, and the analytic structure associated with black-hole geometry are treated as mutually constrained.