Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Backreaction of a massless minimally coupled scalar field from
  inflationary quantum fluctuations   In this paper we study a massless, minimally coupled scalar field in a FLRW
spacetime with periods of different constant deceleration parameter. We assume
the Bunch-Davies vacuum during inflation and then use a sudden matching
approximation to match it onto radiation era and subsequently onto matter era.
We then proceed to calculate the one-loop energy-momentum tensor from the
inflationary quantum vacuum fluctuations in different eras. The energy-momentum
tensor has the form of an ideal (quantum) fluid, characterized by an equation
of state. When compared with the background, far away from the matching the
quantum energy density in radiation era exhibits a contribution that grows
logarithmically with the scale factor. In matter era the ratio of the quantum
to classical fluid settles eventually to a tiny constant, (rho_q) / (rho) =
10^(-13) for a grand unified scale inflation. Curiously, the late time scaling
of quantum fluctuations suggests that they contribute a little to the dark
matter of the Universe, provided that it clusters as cold dark matter, which
needs to be checked.

32
The categories of this paper are: atom-ph
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
25
The categories of this paper are: patt-sol
29
The categories of this paper are: funct-an
2
The categories of this paper are: math
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
33
The categories of this paper are: plasm-ph
13
The categories of this paper are: quant-ph
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph