Hydrodynamical properties of back reacted thermal plasma with finite 't Hooft coupling correction

TL;DR

This work uses the AdS/CFT correspondence to study the hydrodynamic properties of a backreacted $\mathcal{N}=4$ SYM plasma with finite coupling corrections, modeled by a five-dimensional Einstein-Gauss-Bonnet gravity coupled to a string cloud. Observables including drag force, $q\bar{q}$ screening length, jet quenching parameter, and rotating-probe energy loss are computed as functions of temperature, flavour density, and Gauss-Bonnet coupling, revealing that higher density and coupling corrections generally enhance energy loss while reducing binding in bound states. A closed-form expression for the viscosity-to-entropy ratio, $\eta/s = (1/(4\pi))(1 - 8\alpha/l^2 - (4\alpha a u_h^3)/(3 l^6))$, shows possible deviations from the KSS bound within a permitted region of parameter space, indicating the plasma can behave as a near-perfect fluid under certain conditions. The results demonstrate how finite coupling corrections and string-density backreaction modify transport and bound-state properties, with parallel $q\bar{q}$ configurations remaining more stable and rotating-probe dynamics displaying intricate interference among rotational, drag, and vacuum radiation channels, offering insights for strongly coupled QGP phenomenology.

Abstract

In this work, holographic approach has been used to analyse the hydrodynamical properties of $\mathcal{N}=4$ Super Yang-Mills thermal plasma with subleading 't Hooft coupling correction and flavour quarks dual to the AdS Gauss-Bonnet gravity in the presence of string cloud. The drag exerted on an external probe quark while translating through the thermal plasma enhances with probe velocity, flavour quark density, temperature and finite coupling correction. The jet quenching parameter gets enhanced on increase of flavour quark density, temperature and finite coupling correction. Quark-antiquark screening length is observed to reduce with rapidity parameter, flavour quark density, finite coupling correction and temperature which suggests an early transition to the thermal plasma phase of QGP. The screening length is found to be larger for the parallel orientation compared to the perpendicular configuration. Finally, the rotational dynamics of the heavy probe quark is studied. The rotational and drag energy loss increases with angular frequency and quark density, but is almost independent of the 't Hooft coupling.

Figures (18)

• Figure 1: Plot of forbidden region where $\frac{\eta}{s}$ is not positive in $T,\,a,\,\alpha$ space.
• Figure 2: Plot of drag force $F$ with respect to string density $a$ and GB coefficient $\alpha$ for different set of $T$ and velocity $v$.
• Figure 3: $L^{\perp}$ vs $a$ and $\alpha$ for different set of values of $\beta$, $T$ and $W$.
• Figure 4: $L^{\perp}$ vs $W$ for: (a) fixed parameters $T,\,\beta,\,\alpha$ and different $a$ and (b) fixed parameters $a,\,\beta,\,T$ and different $\alpha$.
• Figure 5: $V$ vs $L^\perp$ for: (a) fixed parameters $T,\,\beta,\,\alpha$ and different $a$ and (b) fixed parameters $a,\,\beta,\,T$ and different $\alpha$.