Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Absorption free superluminal light propagation in a three level
  pump-probe system   We investigate the dispersion and the absorption properties of a weak probe
field in a three-level pump-probe atomic system. It is shown that the slope of
dispersion changes from positive to negative just with the intensity of the
coherent or indirect incoherent pumping fields. It is demonstrated that the
absorption free superluminal light propagation is appeared in this system.

11
The categories of this paper are: hep-lat
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
37
The categories of this paper are: supr-con
19
The categories of this paper are: eess
12
The categories of this paper are: nucl-th
31
The categories of this paper are: ao-sci
9
The categories of this paper are: nlin
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
32
The categories of this paper are: atom-ph
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc
25
The categories of this paper are: patt-sol
35
The categories of this paper are: mtrl-th