- 著者
- Hatta Y. Iancu E. Mueller A. H.
- 出版者
- Institute of Physics Publishing
- 雑誌
- Journal of high energy physics (ISSN:11266708)
- 巻号頁・発行日
- vol.2008, no.5, pp.37, 2008-05
- 被引用文献数
- 101 106
Within the framework of the AdS/CFT correspondence, we study the timeevolution of an energetic R-current propagating through a finite temperature, stronglycoupled, N = 4 SYM plasma and propose a physical picture for our results. In thispicture, the current splits into a pair of massless partons, which then evolve via successivebranchings, in such a way that energy is quasi-democratically divided among the productsof a branching. We point out a duality between the transverse size of the partonic systemproduced through branching and the radial distance traveled by the dual Maxwell wave inthe AdS geometry. For a time-like current, the branching occurs already in the vacuum,where it gives rise to a system of low-momentum partons isotropically distributed in thetransverse plane. But at finite temperature, the branching mechanism is modified by themedium, in that the rate for parton splitting is enhanced by the transfer of transversemomentum from the partons to the plasma. This mechanism, which controls the partonenergy loss, is sensitive to the energy density in the plasma, but not to the details of thethermal state. We compute the lifetime of the current for various kinematical regimes andprovide physical interpretations for other, related, quantities, so like the meson screeninglength, the drag force, or the trailing string, that were previously computed via AdS/CFTtechniques.
- 著者
- Hatta Y. Iancu E. Mueller A. H. Triantafyllopoulos D. N.
- 出版者
- Published for SISSA by Springer
- 雑誌
- Journal of high energy physics (ISSN:10298479)
- 巻号頁・発行日
- vol.2011, no.2, pp.065, 2011-02
- 被引用文献数
- 19
We show that a source which radiates in the vacuum of the strongly coupled N = 4=4 SYM theory produces an energy distribution which, in the supergravity approximation, has the same space-time pattern as the corresponding classical distribution: the radiation propagates at the speed of light without broadening. We illustrate this on the basis of several examples: a small perturbation propagating down a steady string, a massless particle falling into AdS5, and the decay of a time-like wave-packet. A similar observation was made in Phys. Rev. D81 (2010) 126001 for the case of a rotating string. In all these cases, the absence of broadening is related to the fact that the energy backreaction on the boundary arises exclusively from the bulk perturbation at, or near, the boundary. This is so since bulk sources which propagate in AdS5 at the speed of light do not generate any energy on the boundary. We interpret these features as an artifact of the supergravity approximation, which fails to encode quantum mechanical fluctuations that should be present even in the strong coupling limit. We argue that such fluctuations should enter the dual string theory as longitudinal string fluctuations, which are not suppressed at strong coupling. We heuristically estimate the effects of such fluctuations and argue that they restore the broadening of the radiation, in agreement with expectations from both quantum mechanics and the ultraviolet/infrared correspondence.