Transport peak in thermal spectral function of N=4 supersymmetric Yang-Mills plasma at intermediate coupling

Journal article

We study the structure of thermal spectral function of the stress-energy tensor in 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 nonperturbatively 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.

Authors: Casalderrey-Solana, J; Grozdanov, S; Starinets, A

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review Letters
• Volume: 121
• Issue: 19
• Article number: 191603
• Publication date: 2018-11-09
• Acceptance date: 2018-11-09
• DOI: 10.1103/PhysRevLett.121.191603
• EISSN: 1079-7114
• ISSN: 0031-9007
• Keywords: hep-th; hep-lat; nucl-th; hep-ph