Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Thermal Conditions for Scalar Bosons in a Curved Space Time   The conditions that allow us to consider the vacuum expectation value of the
energy-momentum tensor as a statistical average, at some particular
temperature, are given. When the mean value of created particles is stationary,
a planckian distribution for the field modes is obtained. In the massless
approximation, the temperature dependence is as that corresponding to a
radiation dominated Friedmann-like model.

19
The categories of this paper are: eess
6
The categories of this paper are: astro-ph
13
The categories of this paper are: quant-ph
30
The categories of this paper are: q-alg
36
The categories of this paper are: cmp-lg
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
20
The categories of this paper are: acc-phys
29
The categories of this paper are: funct-an
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
28
The categories of this paper are: alg-geom
1
The categories of this paper are: cs
24
The categories of this paper are: dg-ga
9
The categories of this paper are: nlin
4
The categories of this paper are: cond-mat