Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Multiple scattering of light by atoms in the weak localization regime   Coherent backscattering is a multiple scattering interference effect which
enhances the diffuse reflection off a disordered sample in the backward
direction. Classically, the enhanced intensity is twice the average background
under well chosen experimental conditions. We show how the quantum internal
structure of atomic scatterers leads to a significantly smaller enhancement.
Theoretical results for double scattering in the weak localization regime are
presented which confirm recent experimental observations.

21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
5
The categories of this paper are: gr-qc
9
The categories of this paper are: nlin
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
8
The categories of this paper are: hep-ex