Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Origin of the inner ring in photoluminescence patterns of quantum well
  excitons   In order to explain and model the inner ring in photoluminescence (PL)
patterns of indirect excitons in GaAs/AlGaAs quantum wells (QWs), we develop a
microscopic approach formulated in terms of coupled nonlinear equations for the
diffusion, thermalization and optical decay of the particles. The origin of the
inner ring is unambiguously identified: it is due to cooling of indirect
excitons in their propagation from the excitation spot. We infer that in our
high-quality structures the in-plane diffusion coefficient is about 10-30cm^2/s
and the amplitude of the disorder potential is about 0.45meV.

27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
30
The categories of this paper are: q-alg
33
The categories of this paper are: plasm-ph
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
37
The categories of this paper are: supr-con
14
The categories of this paper are: math-ph
11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
1
The categories of this paper are: cs
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
26
The categories of this paper are: bayes-an