Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Einstein and Jordan frames reconciled: a frame-invariant approach to
  scalar-tensor cosmology   Scalar-Tensor theories of gravity can be formulated in different frames, most
notably, the Einstein and the Jordan one. While some debate still persists in
the literature on the physical status of the different frames, a frame
transformation in Scalar-Tensor theories amounts to a local redefinition of the
metric, and then should not affect physical results. We analyze the issue in a
cosmological context. In particular, we define all the relevant observables
(redshift, distances, cross-sections, ...) in terms of frame-independent
quantities. Then, we give a frame-independent formulation of the Boltzmann
equation, and outline its use in relevant examples such as particle freeze-out
and the evolution of the CMB photon distribution function. Finally, we derive
the gravitational equations for the frame-independent quantities at first order
in perturbation theory. From a practical point of view, the present approach
allows the simultaneous implementation of the good aspects of the two frames in
a clear and straightforward way.

22
The categories of this paper are: chao-dyn
4
The categories of this paper are: cond-mat
14
The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
27
The categories of this paper are: comp-gas
32
The categories of this paper are: atom-ph
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
9
The categories of this paper are: nlin
20
The categories of this paper are: acc-phys
24
The categories of this paper are: dg-ga
3
The categories of this paper are: physics
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci