Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gauge-Invariant Cosmological Perturbations in Generalized Einstein
  Theories   Using the covariant approach and conformal transformations, we present a
gauge-invariant formalism for cosmological perturbations in generalized
Einstein theories (GETs), including the Brans-Dicke theory, theories with a
non-minimally coupled scalar field and certain curvature-squared theories. We
find an enhancement in the growth rate of density perturbations in the
Brans-Dicke theory, and discuss attractive features of GETs in the structure
formation process.

9
The categories of this paper are: nlin
18
The categories of this paper are: econ
15
The categories of this paper are: nucl-ex
36
The categories of this paper are: cmp-lg
14
The categories of this paper are: math-ph
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
26
The categories of this paper are: bayes-an
4
The categories of this paper are: cond-mat
30
The categories of this paper are: q-alg
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
24
The categories of this paper are: dg-ga
0
The categories of this paper are: hep-ph