Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: On the background in the $\gamma p \to \omega(\pi^0\gamma) p$ reaction
  and mixed event simulation   In this paper we evaluate sources of background for the $\gamma p \to \omega
p$, with the $\omega$ detected through its $\pi^0 \gamma$ decay channel, to
compare with the experiment carried out at ELSA. We find background from
$\gamma p \to \pi^0 \pi^0 p$ followed by decay of a $\pi^0$ into two $\gamma$,
recombining one $\pi^0$ and one $\gamma$, and from the $\gamma p \to \pi^0 \eta
p$ reaction with subsequent decay of the $\eta$ into two photons. This
background accounts for the data at $\pi^0 \gamma$ invariant masses beyond 700
MeV, but strength is missing at lower invariant masses which was attributed to
photon misidentification events, which we simulate to get a good reproduction
of the experimental background. Once this is done, we perform an event mixing
simulation to reproduce the calculated background and we find that the method
provides a good description of the background at low $\pi^0 \gamma$ invariant
masses but fakes the background at high invariant masses, making background
events at low invariant masses, which are due to $\gamma$ misidentification
events, responsible for the background at high invariant masses which is due to
the $\gamma p \to \pi^0 \pi^0 p$ and $\gamma p \to \pi^0 \eta p$ reactions.

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The categories of this paper are: hep-ph
35
The categories of this paper are: mtrl-th
3
The categories of this paper are: physics
36
The categories of this paper are: cmp-lg
20
The categories of this paper are: acc-phys
1
The categories of this paper are: cs
17
The categories of this paper are: q-fin
9
The categories of this paper are: nlin
7
The categories of this paper are: hep-th
14
The categories of this paper are: math-ph
23
The categories of this paper are: solv-int
28
The categories of this paper are: alg-geom
34
The categories of this paper are: chem-ph
19
The categories of this paper are: eess
33
The categories of this paper are: plasm-ph
37
The categories of this paper are: supr-con