Aspects of the Screening Length and Drag Force in Two Alternative Gravity Duals of the Quark-gluon Plasma

Abstract

We compute the screening length of mesons with different angular momentum $J$ from two gravity dual theories. Both the asymptotically $Ad{S}_5$ and Sakai-Sugimoto metrics are considered in the calculations. Using the dual description of the quark as a classical string ending on the probe brane, we obtain the interacting potential between the heavy quark and antiquark after rotating the background metric. The result shows that the screening length of mesons with different $J$ is well fit to $a_J/T$. The constant $a_J$ is determined for $J=0,1,2$ by taking advantage of numerical techniques. Finally, we calculate the drag force and relaxation times from the Sakai-Sugimoto metric and compare with the ones obtained in the $Ad{S}_5$. The application of our result to charmonium and bottomonium at RHIC and LHC is briefly discussed.

Comments: 18 pages, 6 figures, 2 tables, version to appear in JHEP, acknowledgment added