Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Exclusive $\pi^+\pi^-$ Production at the LHC with Forward Proton Tagging   A process of Central Exclusive $\pi^+\pi^-$ production in proton-proton
collisions and its theoretical description is presented. A possibility of its
measurement, during the special low luminosity LHC runs, with the help of the
ATLAS central detector for measuring pions and the ALFA stations for tagging
the scattered protons is studied. A visible cross section is estimated to be 21
$\mu$b for $\sqrt{s}=7$ TeV, which gives over 2000 events for 100 $\mu$b$^{-1}$
of integrated luminosity. Differential distributions in pion pseudorapidities,
pion and proton transverse momenta as well as $\pi^+\pi^-$ invariant mass are
shown and discussed.

27
The categories of this paper are: comp-gas
14
The categories of this paper are: math-ph
26
The categories of this paper are: bayes-an
5
The categories of this paper are: gr-qc
28
The categories of this paper are: alg-geom
17
The categories of this paper are: q-fin
10
The categories of this paper are: q-bio
31
The categories of this paper are: ao-sci
22
The categories of this paper are: chao-dyn
12
The categories of this paper are: nucl-th
34
The categories of this paper are: chem-ph
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
18
The categories of this paper are: econ
11
The categories of this paper are: hep-lat