The complex life of hydrodynamic modes
Journal of High Energy Physics Springer Science and Business Media LLC 2019:11 (2019) 97
Convergence of the Gradient Expansion in Hydrodynamics
Physical Review Letters American Physical Society (APS) 122:25 (2019) 251601
Adding new branches to the “Christmas tree” of the quasinormal spectrum of black branes
Journal of High Energy Physics Springer Nature 2019:4 (2019) 80
Transport peak in thermal spectral function of ${\cal N}=4$ supersymmetric Yang-Mills plasma at intermediate coupling
Physical Review Letters American Physical Society (2018)
Abstract:
We study the structure of thermal spectral function of the stress-energy tensor in ${\cal N}=4$ supersymmetric Yang-Mills theory at intermediate 't Hooft coupling and infinite number of colors. In gauge-string duality, this analysis reduces to the study of classical bulk supergravity with higher-derivative corrections, which correspond to (inverse) coupling corrections on the gauge theory side. We extrapolate the analysis of perturbative leading-order corrections to intermediate coupling by non-perturbatively solving the equations of motion of metric fluctuations dual to the stress-energy tensor at zero spatial momentum. We observe the emergence of a separation of scales in the analytic structure of the thermal correlator associated with two types of characteristic relaxation modes. As a consequence of this separation, the associated spectral function exhibits a narrow structure in the small frequency region which controls the dynamics of transport in the theory and may be described as a transport peak typically found in perturbative, weakly interacting thermal field theories. We compare our results with generic expectations drawn from perturbation theory, where such a structure emerges as a consequence of the existence of quasiparticles.Second-order transport, quasinormal modes and zero-viscosity limit in the Gauss-Bonnet holographic fluid
Journal of High Energy Physics Springer Berlin Heidelberg 2017:3 (2017) 166