Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Identification of perturbation modes and controversies in ekpyrotic
  perturbations   If the linear perturbation theory is valid through the bounce, the surviving
fluctuations from the ekpyrotic scenario (cyclic one as well) should have very
blue spectra with suppressed amplitude for the scalar-type structure. We derive
the same (and consistent) result using the curvature perturbation in the
uniform-field (comoving) gauge and in the zero-shear gauge. Previously, Khoury
et al. interpreted results from the latter gauge condition incorrectly and
claimed the scale-invariant spectrum, thus generating controversy in the
literature. We also correct similar errors in the literature based on wrong
mode identification and joining condition. No joining condition is needed for
the derivation.

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The categories of this paper are: chao-dyn
25
The categories of this paper are: patt-sol
31
The categories of this paper are: ao-sci
8
The categories of this paper are: hep-ex
30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
13
The categories of this paper are: quant-ph
14
The categories of this paper are: math-ph
34
The categories of this paper are: chem-ph
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
35
The categories of this paper are: mtrl-th
36
The categories of this paper are: cmp-lg
15
The categories of this paper are: nucl-ex