AdS/CFT correspondence, quasinormal modes, and thermal correlators inN=4supersymmetric Yang-Mills theory

We use the Lorentzian AdS/CFT prescription to find the poles of the retarded thermal Green’s functions of $\mathcal{N}=4\mathrm{}$ $\mathrm{SU}\left(N\right)\mathrm{}$ supersymmetric Yang-Mills theory in the limit of large N and large ’t Hooft coupling. In the process, we propose a natural definition for quasinormal modes in an asymptotically AdS spacetime, with boundary conditions dictated by the AdS/CFT correspondence. The corresponding frequencies determine the dispersion laws for the quasiparticle excitations in the dual finite-temperature gauge theory. Correlation functions of operators dual to massive scalar, vector and gravitational perturbations in a five-dimensional AdS-Schwarzschild background are considered. We find asymptotic formulas for quasinormal frequencies in the massive scalar and tensor cases, and an exact expression for vector perturbations. In the long-distance, low-frequency limit we recover results of the hydrodynamic approximation to thermal Yang-Mills theory.