Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Approaches to linear local gauge-invariant observables in inflationary
  cosmologies   We review and relate two recent complementary constructions of linear local
gauge-invariant observables for cosmological perturbations in generic spatially
flat single-field inflationary cosmologies. After briefly discussing their
physical significance, we give explicit, covariant and mutually invertible
transformations between the two sets of observables, thus resolving any doubts
about their equivalence. In this way, we get a geometric interpretation and
show the completeness of both sets of observables, while previously each of
these properties was available only for one of them.

30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
7
The categories of this paper are: hep-th
19
The categories of this paper are: eess
37
The categories of this paper are: supr-con
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
33
The categories of this paper are: plasm-ph
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
25
The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
36
The categories of this paper are: cmp-lg
10
The categories of this paper are: q-bio