Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measurement of Elastic omega Photoproduction at HERA   The reaction $\gamma p \rightarrow \omega p$ $(\omega \rightarrow
\pi^+\pi^-\pi^0$ and $\pi^0\rightarrow\gamma\gamma)$ has been studied in $ep$
interactions using the ZEUS detector at photon-proton centre-of-mass energies
between $70$ and $90 GeV$ and $|t| < 0.6 GeV^2$, where $t$ is the squared four
momentum transferred at the proton vertex.The elastic \ome photoproduction
cross section has been measured to be $\sigma_{\gamma p\rightarrow \omega p} =
1.21\pm 0.12\pm 0.23 \mu b$. The differential cross section $d\sigma_{\gamma
p\rightarrow \omega p} /d|t|$ has an exponential shape $e^{-b |t|}$ with a
slope $b = 10.0\pm 1.2\pm 1.3 GeV^{-2}$. The angular distributions of the decay
pions are consistent with s-channel helicity conservation. When compared to low
energy data, the features of $\omega$ photoproduction as measured at HERA
energies are in agreement with those of a soft diffractive process. Previous
measurements of the $\rho^0$ and $\phi$ photoproduction cross sections at HERA
show a similar behaviour.

27
The categories of this paper are: comp-gas
2
The categories of this paper are: math
1
The categories of this paper are: cs
6
The categories of this paper are: astro-ph
3
The categories of this paper are: physics
18
The categories of this paper are: econ
25
The categories of this paper are: patt-sol
20
The categories of this paper are: acc-phys
9
The categories of this paper are: nlin
32
The categories of this paper are: atom-ph
29
The categories of this paper are: funct-an
30
The categories of this paper are: q-alg
31
The categories of this paper are: ao-sci
21
The categories of this paper are: adap-org
15
The categories of this paper are: nucl-ex
5
The categories of this paper are: gr-qc