Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantum Fluctuations and Particle Production of Coherently Oscillating
  Inflaton   We study a massive inflaton minimally coupled to the FRW Universe using the
semiclassical gravity derived from canonical quantum gravity. It is found that
the semiclassical quantum gravity leads to the power-law expansion $t^{2/3}$ in
an oscillatory phase of the inflaton. The particle production of the inflaton
in the expanding Universe restricts the duration of stable coherent
oscillations and parametric resonance. The semiclassical gravity shows a
significant difference that the Hubble constant does not oscillate in contrast
with the oscillatory behavior in classical gravity.

13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
33
The categories of this paper are: plasm-ph
36
The categories of this paper are: cmp-lg
26
The categories of this paper are: bayes-an
6
The categories of this paper are: astro-ph
16
The categories of this paper are: stat
1
The categories of this paper are: cs
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
4
The categories of this paper are: cond-mat
34
The categories of this paper are: chem-ph
14
The categories of this paper are: math-ph
5
The categories of this paper are: gr-qc
2
The categories of this paper are: math
28
The categories of this paper are: alg-geom