Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Generation of particle number asymmetry in expanding universe   We study creation and time evolution of particle number asymmetry with
nonequilibrium quantum field theory. We introduce a model of a neutral scalar
and a complex scalar and it has CP violating and particle number violating
features. Starting with an initial condition specified by density operator, we
show how particle number asymmetry can be generated through interaction. We
investigate the time evolution of particle number asymmetry of universe using
perturbation method.

16
The categories of this paper are: stat
20
The categories of this paper are: acc-phys
12
The categories of this paper are: nucl-th
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
8
The categories of this paper are: hep-ex
11
The categories of this paper are: hep-lat
23
The categories of this paper are: solv-int
29
The categories of this paper are: funct-an
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
34
The categories of this paper are: chem-ph
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
35
The categories of this paper are: mtrl-th
33
The categories of this paper are: plasm-ph