Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Extragalactic Propagation of Ultra-High Energy Cosmic Rays   More than 100 years after the discovery of cosmic rays and various
experimental efforts, the origin of ultra-high energy cosmic rays (E > 100 PeV)
remains unclear. The understanding of production and propagation effects of
these highest energetic particles in the universe is one of the most intense
research fields of high-energy astrophysics. With the advent of advanced
simulation engines developed during the last couple of years, and the increase
of experimental data, we are now in a unique position to model source and
propagation parameters in an unprecedented precision and compare it to measured
data from large scale observatories. In this paper we revisit the most
important propagation effects of cosmic rays through photon backgrounds and
magnetic fields and introduce recent developments of propagation codes.
Finally, by comparing the results to experimental data, possible implications
on astrophysical parameters are given.

29
The categories of this paper are: funct-an
3
The categories of this paper are: physics
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
8
The categories of this paper are: hep-ex
9
The categories of this paper are: nlin
34
The categories of this paper are: chem-ph
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
31
The categories of this paper are: ao-sci
17
The categories of this paper are: q-fin
32
The categories of this paper are: atom-ph
20
The categories of this paper are: acc-phys
7
The categories of this paper are: hep-th