Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Search for eta-mesic helium via deuteron-deuteron reactions with the
  WASA-at-COSY facility   The eta-mesic nuclei in which the eta meson is bound with nucleus via strong
interaction was postulated already in 1986, however till now no experiment
confirmed empirically its existence. The discovery of this new kind of an
exotic nuclear matter would be very important for better understanding of the
eta meson structure and its interaction with nucleons. The search for eta-mesic
helium is carried out with high statistic and high acceptance with the
WASA-at-COSY detection setup in the Forschungszentrum Julich. The search is
conducted via the measurement of the excitation function for the chosen decay
channels of the 4He-eta system. Untill now two reactions dd->(4He-eta)bs->3He p
pi- and dd->(4He-eta)bs->3He n pi0 have been measured with the beam momentum
ramped around the eta production threshold. This report includes the
description of experimental method and status of the analysis.

17
The categories of this paper are: q-fin
23
The categories of this paper are: solv-int
2
The categories of this paper are: math
9
The categories of this paper are: nlin
37
The categories of this paper are: supr-con
32
The categories of this paper are: atom-ph
27
The categories of this paper are: comp-gas
25
The categories of this paper are: patt-sol
36
The categories of this paper are: cmp-lg
22
The categories of this paper are: chao-dyn
21
The categories of this paper are: adap-org
18
The categories of this paper are: econ
10
The categories of this paper are: q-bio
34
The categories of this paper are: chem-ph
20
The categories of this paper are: acc-phys
19
The categories of this paper are: eess