Instruct: Identify the main and secondary category of Arxiv papers based on the titles
Query: Search for long-lived particles in events with photons and missing
  energy in proton-proton collisions at sqrt(s) = 7 TeV
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
19
The categories of this paper are: eess
27
The categories of this paper are: comp-gas
12
The categories of this paper are: nucl-th
11
The categories of this paper are: hep-lat
24
The categories of this paper are: dg-ga
14
The categories of this paper are: math-ph
1
The categories of this paper are: cs
7
The categories of this paper are: hep-th
5
The categories of this paper are: gr-qc
15
The categories of this paper are: nucl-ex
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
3
The categories of this paper are: physics