52,625 research outputs found
A Modified "Bottom-up" Thermalization in Heavy Ion Collisions
In the initial stage of the bottom-up picture of thermalization in heavy ion
collisions, the gluon distribution is highly anisotropic which can give rise to
plasma instability. This has not been taken account in the original paper. It
is shown that in the presence of instability there are scaling solutions, which
depend on one parameter, that match smoothly onto the late stage of bottom-up
when thermalization takes place.Comment: 8 pages and 1 embedded figure, talk presented at the Workshop on
"Quark-Gluon Plasma Thermalization", Vienna, Austria, 10-12 August 200
Multiple scattering of light by atoms with internal degeneracy
An analytical microscopic theory for the resonant multiple scattering of
light by cold atoms with arbitrary internal degeneracy is presented. It permits
to calculate the average amplitude and the average intensity for one-photon
states of the full transverse electromagnetic field in a dilute medium of
unpolarized atoms. Special emphasis is laid upon an analysis in terms of
irreducible representations of the rotation group. It allows to sum explicitly
the ladder and maximally crossed diagrams, giving the average intensity in the
Boltzmann approximation and the interference corrections responsible for weak
localization and coherent backscattering. The exact decomposition into field
modes shows that the atomic internal degeneracy contributes to the
depolarization of the average intensity and suppresses the interference
corrections. Static as well as dynamic quantities like the transport velocity,
diffusion constants and relaxation times for all field modes and all atomic
transitions are derived.Comment: Corrected minor errors. Slightly extended version of the article
appeared in prin
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