Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Slow group velocity and Cherenkov radiation   We theoretically study the effect of ultraslow group velocities on the
emission of Vavilov-Cherenkov radiation in a coherently driven medium. We show
that in this case the aperture of the group cone on which the intensity of the
radiation peaks is much smaller than that of the usual wave cone associated
with the Cherenkov coherence condition. We show that such a singular behaviour
may be observed in a coherently driven ultracold atomic gas.

11
The categories of this paper are: hep-lat
21
The categories of this paper are: adap-org
22
The categories of this paper are: chao-dyn
16
The categories of this paper are: stat
17
The categories of this paper are: q-fin
33
The categories of this paper are: plasm-ph
18
The categories of this paper are: econ
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
25
The categories of this paper are: patt-sol
24
The categories of this paper are: dg-ga
6
The categories of this paper are: astro-ph
14
The categories of this paper are: math-ph
36
The categories of this paper are: cmp-lg