Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Production of eta and eta-prime mesons via the quasi-free proton-neutron
  interaction   A comparison of the close-to-threshold total cross sections for the eta-prime
meson production in both the pp --> pp eta-prime and pn --> pn eta-prime
reactions should provide insight into the flavour-singlet (perhaps also into
gluonium) content of the eta-prime meson and the relevance of quark-gluon or
hadronic degrees of freedom in the creation process. The excitation function
for the reaction pp --> pp eta-prime has been already established. At present,
experimental investigations of the quasi-free pn --> pn X reactions are carried
out at the COSY-11 facility using a beam of stochastically cooled protons and
the deuteron cluster target. A method of measurement and preliminary results
from the test experiments of the pn --> pn eta reaction are presented in this
report.

31
The categories of this paper are: ao-sci
4
The categories of this paper are: cond-mat
24
The categories of this paper are: dg-ga
23
The categories of this paper are: solv-int
8
The categories of this paper are: hep-ex
17
The categories of this paper are: q-fin
28
The categories of this paper are: alg-geom
13
The categories of this paper are: quant-ph
7
The categories of this paper are: hep-th
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
32
The categories of this paper are: atom-ph
26
The categories of this paper are: bayes-an
25
The categories of this paper are: patt-sol
0
The categories of this paper are: hep-ph