Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gravitational Particle Creation in a Stiff Matter Dominated Universe   A scenario for gravitational particle creation in a stiff matter dominated
flat Friedmann-Robertson-Walker universe is presented. The primary creation of
scalar particles is calculated using quantum field theory in curved spacetime
and it is found to be strongly dependent on the scalar mass and the expansion
parameter of the universe. The particle creation is most effective for a very
massive scalar field and large expansion parameter. We apply the results to
cosmology and calculate an upper bound for the equilibrium temperature of the
secondary particles created by the scalar field decay.

20
The categories of this paper are: acc-phys
13
The categories of this paper are: quant-ph
3
The categories of this paper are: physics
21
The categories of this paper are: adap-org
37
The categories of this paper are: supr-con
34
The categories of this paper are: chem-ph
0
The categories of this paper are: hep-ph
22
The categories of this paper are: chao-dyn
23
The categories of this paper are: solv-int
35
The categories of this paper are: mtrl-th
14
The categories of this paper are: math-ph
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
31
The categories of this paper are: ao-sci
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin