Stirring Strongly Coupled Plasma
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Author(s)
Fadafan, Kazem Bitaghsir
Liu, Hong
Rajagopal, Krishna
Wiedemann, Urs Achim
Date Issued
February 2009
Journal
European Physical Journal. C, Particles and Fields
Publisher
Springer Berlin Heidelberg
Citation
Fadafan, Kazem Bitaghsir, et al "Stirring strongly coupled plasma." The European Physical Journal C - Particles and Fields 61.4 (2009): 553-567.
Version
Original manuscript
Abstract
We determine the energy it takes to move a test quark along a circle of radius L with angular frequency ω through the strongly coupled plasma of $\mathcal{N}=4$ supersymmetric Yang–Mills (SYM) theory. We find that for most values of L and ω the energy deposited by stirring the plasma in this way is governed either by the drag force acting on a test quark moving through the plasma in a straight line with speed v=L ω or by the energy radiated by a quark in circular motion in the absence of any plasma, whichever is larger. There is a continuous crossover from the drag-dominated regime (ω≲π T(1−v [superscript 2])[superscript 3/4], meaning ω≲π T and L small enough) to the radiation-dominated regime (ω≳π T(1−v [superscript 2])[superscript 3/4]). In the crossover regime we find evidence for significant destructive interference between energy loss due to drag and due to radiation as if in vacuum. The rotating quark thus serves as a model system in which the relative strength of, and interplay between, two different mechanisms of parton energy loss is accessible via a controlled classical gravity calculation. We close by speculating on the implications of our results for a quark that is moving through the plasma in a straight line while decelerating, although in this case the classical calculation breaks down at the same value of the deceleration as the one at which the radiation-dominated regime sets in.
MIT Department
Massachusetts Institute of Technology. Center for Theoretical Physics
Massachusetts Institute of Technology. Department of Physics
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DOI of Published Version
http://dx.doi.org/10.1140/epjc/s10052-009-0885-6
