Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Particle-antiparticle asymmetries from annihilations   An extensively studied mechanism to create particle-antiparticle asymmetries
is the out-of-equilibrium and CP violating decay of a heavy particle. Here we
instead examine how asymmetries can arise purely from 2 <-> 2 annihilations
rather than from the usual 1 <-> 2 decays and inverse decays. We review the
general conditions on the reaction rates that arise from S-matrix unitarity and
CPT invariance, and show how these are implemented in the context of a simple
toy model. We formulate the Boltzmann equations for this model, and present an
example solution.

23
The categories of this paper are: solv-int
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
22
The categories of this paper are: chao-dyn
1
The categories of this paper are: cs
3
The categories of this paper are: physics
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an
7
The categories of this paper are: hep-th
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
32
The categories of this paper are: atom-ph