Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Superfluidity of the BEC at finite temperature   We use the classical fields approximation to study a translational flow of
the condensate with respect to the thermal cloud in a weakly interacting Bose
gas. We study both, subcritical and supercritical relative velocity cases and
analyze in detail a state of stationary flow which is reached in the dynamics.
This state corresponds to the thermal equilibrium, which is characterized by
the relative velocity of the condensate and the thermal cloud. The
superfluidity manifests itself in the existence of many thermal equilibria
varying in (the value of this velocity) the relative velocity between the
condensate and the thermal cloud. We pay a particular attention to excitation
spectra in a phonon as well as in a particle regime. Finally, we introduce a
measure of the amount of the superfluid fraction in a weakly interacting Bose
gas, allowing for the precise distinction between the superfluid and the
condensed fractions in a single and consistent framework.

11
The categories of this paper are: hep-lat
31
The categories of this paper are: ao-sci
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
22
The categories of this paper are: chao-dyn
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
33
The categories of this paper are: plasm-ph
19
The categories of this paper are: eess
13
The categories of this paper are: quant-ph
25
The categories of this paper are: patt-sol
14
The categories of this paper are: math-ph
30
The categories of this paper are: q-alg
37
The categories of this paper are: supr-con
9
The categories of this paper are: nlin
23
The categories of this paper are: solv-int