Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Reinvestigation of $pp\to pp\pi^0$ and $pp\to pp\eta$ at threshold   $pp\to pp\pi^0$ and $pp\to pp\eta$ were considered close to threshold. The
pion production was found not only to be dominated by impulse approximation
(IA) and rescattering contributions, but also strongly by box-diagrams,
resonances and heavy-meson exchanges. New relevant contributions for the IA
were found. The role of the offshell behaviour of nucleon-resonance couplings
($P_{11}(1440), S_{11}(1535)$) and of interference effects for the eta
production was investigated. The results opened a large door for microsopic
understanding of short range physics. A covariant model for $pp\to pp\eta$
being under construction is going to be finished.

30
The categories of this paper are: q-alg
24
The categories of this paper are: dg-ga
16
The categories of this paper are: stat
11
The categories of this paper are: hep-lat
4
The categories of this paper are: cond-mat
35
The categories of this paper are: mtrl-th
0
The categories of this paper are: hep-ph
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
3
The categories of this paper are: physics
9
The categories of this paper are: nlin
1
The categories of this paper are: cs
20
The categories of this paper are: acc-phys
34
The categories of this paper are: chem-ph
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom