Journal of High Energy Physics

, 2010:88 | Cite as

Langevin diffusion of heavy quarks in non-conformal holographic backgrounds

  • Umut Gürsoy
  • Elias Kiritsis
  • Liuba Mazzanti
  • Francesco Nitti
Open Access


The Langevin diffusion process of a relativistic heavy quark in a non-conformal holographic setup is analyzed. The bulk geometry is a general, five-dimensional asymptotically AdS black hole. The heavy quark is described by a trailing string attached to a flavor brane, moving at constant velocity. From the equations describing linearized fluctuations of the string world-sheet, the correlation functions defining a generalized Langevin process are constructed via the AdS/CFT prescription. In the local limit, analytic expressions for the Langevin diffusion and friction coefficients are obtained in terms of the bulk string metric. Modified Einstein relations between these quantities are also derived. The spectral densities associated to the Langevin correlators are analyzed, and simple analytic expressions are obtained in the small and large frequency limits. Finally, a numerical analysis of the jet-quenching parameter, and a comparison to RHIC phenomenology are performed in the case of Improved Holographic QCD. It is shown that the jet-quenching parameter is not enough to describe energy loss of very energetic charm quarks and the full Langevin correlators are needed.


Gauge-gravity correspondence Black Holes QCD 


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© The Author(s) 2010

Open Access This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited.

Authors and Affiliations

  • Umut Gürsoy
    • 1
  • Elias Kiritsis
    • 2
    • 4
  • Liuba Mazzanti
    • 3
  • Francesco Nitti
    • 4
  1. 1.Institute for Theoretical PhysicsUtrecht UniversityUtrechtThe Netherlands
  2. 2.Crete Center for Theoretical Physics, Department of PhysicsUniversity of CreteHeraklionGreece
  3. 3.Departamento de Física de PartículasUniversidade de Santiago de Compostela and Instituto Galego de Física de Altas Enerxías (IGFAE)Santiago de CompostelaSpain
  4. 4.APC, UMR du CNRS 7164, Université Paris 7Paris Cedex 13France

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