Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Particle decays in the presence of a neutrino background   Several non-threshold reactions which may be used to detect the cosmic
neutrino background are presented. The corresponding cross sections are
calculated analytically within the Standard Model. These reactions are
sensitive not only to the electron neutrinos but also to the muon and tau
neutrinos. Some possibilities of experimental observation of the neutrino
background are indicated.

3
The categories of this paper are: physics
11
The categories of this paper are: hep-lat
33
The categories of this paper are: plasm-ph
12
The categories of this paper are: nucl-th
16
The categories of this paper are: stat
1
The categories of this paper are: cs
10
The categories of this paper are: q-bio
7
The categories of this paper are: hep-th
30
The categories of this paper are: q-alg
14
The categories of this paper are: math-ph
28
The categories of this paper are: alg-geom
35
The categories of this paper are: mtrl-th
34
The categories of this paper are: chem-ph
2
The categories of this paper are: math
37
The categories of this paper are: supr-con
26
The categories of this paper are: bayes-an