Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quantization of the massless scalar field in de Sitter spacetime with
  unitary dynamics   We present a Fock quantization with unitary dynamics for the massless scalar
field in de Sitter spacetime.

3
The categories of this paper are: physics
14
The categories of this paper are: math-ph
20
The categories of this paper are: acc-phys
6
The categories of this paper are: astro-ph
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
7
The categories of this paper are: hep-th
4
The categories of this paper are: cond-mat
1
The categories of this paper are: cs
36
The categories of this paper are: cmp-lg
25
The categories of this paper are: patt-sol
17
The categories of this paper are: q-fin
16
The categories of this paper are: stat
8
The categories of this paper are: hep-ex
2
The categories of this paper are: math
24
The categories of this paper are: dg-ga