Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Comments on Superluminal Laser Pulse Propagation   Researchers claim to have observed superluminal (faster than light)
propagation of a laser pulse in a gain medium by a new mechanism in which there
is no distortion of the pulse [Nature, 406, 277 (2000)]. Our analysis shows
that the observed mechanism is due to pulse distortion arising from a
differential gain effect and should not be viewed as superluminal propagation.

17
The categories of this paper are: q-fin
25
The categories of this paper are: patt-sol
26
The categories of this paper are: bayes-an
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
27
The categories of this paper are: comp-gas
7
The categories of this paper are: hep-th
13
The categories of this paper are: quant-ph
31
The categories of this paper are: ao-sci
23
The categories of this paper are: solv-int
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con
12
The categories of this paper are: nucl-th
14
The categories of this paper are: math-ph
21
The categories of this paper are: adap-org