Quasinormal modes of asymptotically AdS black holes can be interpreted as poles of retarded correlators in the dual gauge theory. To determine the response of the system to small external perturbations it is not enough to know the location of the poles: one also needs to know the residues. We compute them for R-charge currents and find that they are complex except for the hydrodynamic mode, whose residue is purely imaginary. For different quasinormal modes the residue grows with momentum q, whereas for the hydrodynamic mode it behaves as a damped oscillation with distinct zeroes at finite q. Similar to collective excitations at weak coupling the hydrodynamic mode decouples at short wavelengths. Knowledge of the residues allows as well to define the time scale t_H from when on the system enters the hydrodynamic regime, restricting the validity of hydrodynamic simulations to times t>t_H.
National Sun Yat-sen University（国立中山大学）；National Taiwan University（国立台湾大学）；National Center for Theoretical Sciences（国家理论科学中心）；Max Planck{-}IAS{-}NTU Center for Particle Physics, Cosmology and Geometry（马克斯·普朗克-国际高等研究院-台湾大学粒子物理、宇宙学与几何中心）
本文通过 bootstrap 方法研究 de Sitter 空间中费米子边界关联函数，推导了费米子交换的切割规则，并展示了守恒 spin-3/2 算子与 de Sitter 几何之间的张力。
Knizhnik-Zamolodchikov equations and the analytic structure of strings in AdS$_3$
Instituto de Astronomía y Física del Espacio (IAFE), CONICET - Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales（空间天体物理学与物理研究所，阿根廷国家科学研究委员会-布宜诺斯艾利斯大学，理学院）；Universidad Abierta Interamericana, Facultad de Arquitectura（泛美开放大学，建筑学院）；Instituto de Física de La Plata - CONICET（拉普拉塔物理研究所，阿根廷国家科学研究委员会）；Departamento de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires（布宜诺斯艾利斯大学理学院物理系）；Instituto de Investigaciones Matemáticas Luis A. Santaló (IMAS), CONICET - Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales（路易斯·A·桑塔洛数学研究所，阿根廷国家科学研究委员会-布宜诺斯艾利斯大学，理学院）
