Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scalar and vector perturbations in a universe with nonlinear perfect
  fluid   We study a three-component universe filled with dust-like matter in the form
of discrete inhomogeneities (e.g., galaxies) and perfect fluids characterized
by linear and nonlinear equations of state. Within the cosmic screening
approach, we develop the theory of scalar and vector perturbations. None of the
energy density contrasts associated with the distinct components is treated as
small. Consequently, the derived equations are valid at both sub- and
super-horizon scales and enable simulations for a variety of cosmological
models.

25
The categories of this paper are: patt-sol
10
The categories of this paper are: q-bio
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
29
The categories of this paper are: funct-an
4
The categories of this paper are: cond-mat
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
27
The categories of this paper are: comp-gas
23
The categories of this paper are: solv-int
19
The categories of this paper are: eess
32
The categories of this paper are: atom-ph
3
The categories of this paper are: physics
24
The categories of this paper are: dg-ga
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat