| Popis: |
We present the first ever AdS/CFT calculation of q for a light quark jet as a function of position or, equivalently, time. Our result does not suffer from the gamma factor blow up of the usual time-independent AdS/CFT heavy quark setup and is qualitatively similar to, but differs by ∼ O ( 1 ) factor from, the light flavor result of Liu, Rajagopal, and Wiedemann. Our findings can be immediately implemented into any q -based energy loss model. Our q derivation relies on our calculation of the average distance squared, s 2 ( t ) , travelled by the endpoint of a string falling in an AdS 3 -Schwarzschild spacetime. The early time behavior is ballistic, s 2 ( t ) ∼ t 2 , but the late time behavior is the usual diffusive Brownian motion, s 2 ( t ) ∼ t . These late time dynamics are universal and depend only on the near-horizon physics, which allows us to generalize our results to arbitrary dimensions and thus make contact with the physics explored by RHIC and LHC. Additionally, we find that AdS/CFT predicts angular ordering for radiation in medium, just as in vacuum, and in contradistinction to weak-coupling, with its anti-angular ordering prediction. Finally, our results also imply, sensibly, that AdS/CFT predicts a smooth interpolation between the angular correlations of open heavy flavor and light flavor observables. |
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