Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of the rare eta->e+e-e+e- decay with the KLOE experiment   We report the first observation of the rare eta->e+e-e+e- decay based on 1.7
fb^{-1} collected by the KLOE experiment at the DAFNE phi-factory. The
selection of the e+e-e+e- final state is fully inclusive of radiation. We have
identified 362 +- 29 events resulting in a branching ratio of (2.4 +-
0.2_stat+bckg +- 0.1_syst) x 10^{-5}.

29
The categories of this paper are: funct-an
28
The categories of this paper are: alg-geom
12
The categories of this paper are: nucl-th
0
The categories of this paper are: hep-ph
37
The categories of this paper are: supr-con
10
The categories of this paper are: q-bio
6
The categories of this paper are: astro-ph
32
The categories of this paper are: atom-ph
25
The categories of this paper are: patt-sol
7
The categories of this paper are: hep-th
31
The categories of this paper are: ao-sci
11
The categories of this paper are: hep-lat
27
The categories of this paper are: comp-gas
16
The categories of this paper are: stat
24
The categories of this paper are: dg-ga
15
The categories of this paper are: nucl-ex