Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Analysing power A_y in the reaction p(pol) p --> p p eta close to
  threshold   Measurements of the eta meson production with a polarised proton beam in the
reaction p(pol) p --> p p eta have been carried out at an excess energy of Q =
40 MeV. The dependence of the analysing power A_y on the polar angle theta^*_q
of the eta meson in the center of mass system (CMS) has been studied. The data
indicate the possibility of an influence of p- and d-waves to the close to
threshold eta production.

10
The categories of this paper are: q-bio
26
The categories of this paper are: bayes-an
24
The categories of this paper are: dg-ga
28
The categories of this paper are: alg-geom
30
The categories of this paper are: q-alg
20
The categories of this paper are: acc-phys
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
4
The categories of this paper are: cond-mat
23
The categories of this paper are: solv-int
36
The categories of this paper are: cmp-lg
27
The categories of this paper are: comp-gas
1
The categories of this paper are: cs
2
The categories of this paper are: math