Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Relativistic Kinetics of Phonon Gas in Superfluids   The relativistic kinetic theory of the phonon gas in superfluids is
developed. The technique of the derivation of macroscopic balance equations
from microscopic equations of motion for individual particles is applied to an
ensemble of quasi-particles. The necessary expressions are constructed in terms
of a Hamilton function of a (quasi-)particle. A phonon contribution into
superfluid dynamic parameters is obtained from energy-momentum balance
equations for the phonon gas together with the conservation law for superfluids
as a whole. Relations between dynamic flows being in agreement with results of
relativistic hydrodynamic consideration are found. Based on the kinetic
approach a problem of relativistic variation of the speed of sound under phonon
influence at low temperature is solved.

10
The categories of this paper are: q-bio
9
The categories of this paper are: nlin
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
2
The categories of this paper are: math
8
The categories of this paper are: hep-ex
22
The categories of this paper are: chao-dyn
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
21
The categories of this paper are: adap-org
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con