Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Scalar and Tensor Inhomogeneities from Dimensional Decoupling   We discuss some perturbative techniques suitable for the gauge-invariant
treatment of the scalar and tensor inhomogeneities of an anisotropic and
homogeneous background geometry whose spatial section naturally decomposes into
the direct product of two maximally symmetric Eucledian manifolds, describing a
general situation of dimensional decoupling in which $d$ external dimensions
evolve (in conformal time) with scale factor $a(\eta)$ and $n$ internal
dimensions evolve with scale factor $b(\eta)$. We analyze the growing mode
problem which typically arises in contracting backgrounds and we focus our
attention on the situation where the amplitude of the fluctuations not only
depends on the external space-time but also on the internal spatial
coordinates. In order to illustrate the possible relevance of this analysis we
compute the gravity waves spectrum produced in some highly simplified model of
cosmological evolution and we find that the spectral amplitude, whose magnitude
can be constrained by the usual bounds applied to the stochastic gravity waves
backgrounds, depends on the curvature scale at which the compactification
occurs and also on the typical frequency of the internal excitations.

23
The categories of this paper are: solv-int
1
The categories of this paper are: cs
13
The categories of this paper are: quant-ph
29
The categories of this paper are: funct-an
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
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
32
The categories of this paper are: atom-ph
2
The categories of this paper are: math
3
The categories of this paper are: physics
28
The categories of this paper are: alg-geom
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
10
The categories of this paper are: q-bio