Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The most energetic particles in the universe   Several issues related to the lensing of ultra-high energy cosmic rays by the
Galactic magnetic field are discussed.

11
The categories of this paper are: hep-lat
34
The categories of this paper are: chem-ph
26
The categories of this paper are: bayes-an
12
The categories of this paper are: nucl-th
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
14
The categories of this paper are: math-ph
7
The categories of this paper are: hep-th
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
19
The categories of this paper are: eess
1
The categories of this paper are: cs
18
The categories of this paper are: econ
21
The categories of this paper are: adap-org
25
The categories of this paper are: patt-sol
13
The categories of this paper are: quant-ph