pQCD vs. AdS/CFT Tested by Heavy Quark Energy Loss
arXiv:0710.0703 · doi:10.1088/0954-3899/35/4/044025
Abstract
We predict the charm and bottom quark nuclear modification factors using weakly coupled pQCD and strongly coupled AdS/CFT drag methods. The log(pT/M_Q)/pT dependence of pQCD loss and the momentum independence of drag loss lead to different momentum dependencies for the R_{AA} predictions. This difference is enhanced by examining a new experimental observable, the double ratio of charm to bottom nuclear modification factors, R^{cb}=R^c_{AA}/R^b_{AA}. At LHC the weakly coupled theory predicts R^{cb} goes to 1; whereas the strongly coupled theory predicts R^{cb} .2 independent of pT. At RHIC the differences are less dramatic, as the production spectra are harder, but the drag formula is applicable to higher momenta, due to the lower temperature.
6 pages, 4 figures. Proceedings for the International Conference on Strangeness in Quark Matter (SQM 2007), Levoca, Slovakia, 24-29 June 2007