Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Signals From the Epoch of Cosmological Recombination   The physical ingredients to describe the epoch of cosmological recombination
are amazingly simple and well-understood. This fact allows us to take into
account a very large variety of physical processes, still finding potentially
measurable consequences for the energy spectrum and temperature anisotropies of
the Cosmic Microwave Background (CMB). In this contribution we provide a short
historical overview in connection with the cosmological recombination epoch and
its connection to the CMB. Also we highlight some of the detailed physics that
were studied over the past few years in the context of the cosmological
recombination of hydrogen and helium. (abrigded)

4
The categories of this paper are: cond-mat
15
The categories of this paper are: nucl-ex
14
The categories of this paper are: math-ph
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
26
The categories of this paper are: bayes-an
30
The categories of this paper are: q-alg
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
32
The categories of this paper are: atom-ph
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
2
The categories of this paper are: math
9
The categories of this paper are: nlin