Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Loss of Quantum Coherence and Positivity of Energy Density in
  Semiclassical Quantum Gravity
36
The categories of this paper are: cmp-lg
28
The categories of this paper are: alg-geom
32
The categories of this paper are: atom-ph
16
The categories of this paper are: stat
10
The categories of this paper are: q-bio
18
The categories of this paper are: econ
12
The categories of this paper are: nucl-th
3
The categories of this paper are: physics
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
15
The categories of this paper are: nucl-ex
11
The categories of this paper are: hep-lat
0
The categories of this paper are: hep-ph
23
The categories of this paper are: solv-int
13
The categories of this paper are: quant-ph
37
The categories of this paper are: supr-con