Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Observation of the antimatter helium-4 nucleus at RHIC   We present the observation of the \Heebar nucleus, the heaviest antinucleus
observed to date. In total, 18 \Heebar counts were detected at the STAR
experiment at RHIC in 10$^{9}$ recorded Au+Au collisions at beam energies of
$\sqrt{s_{NN}}$ = 200 GeV and 62 GeV. The background has been estimated, and
the misidentification probability is found to be lower than 10$^{-11}$.

11
The categories of this paper are: hep-lat
6
The categories of this paper are: astro-ph
21
The categories of this paper are: adap-org
2
The categories of this paper are: math
0
The categories of this paper are: hep-ph
32
The categories of this paper are: atom-ph
1
The categories of this paper are: cs
5
The categories of this paper are: gr-qc
19
The categories of this paper are: eess
34
The categories of this paper are: chem-ph
10
The categories of this paper are: q-bio
27
The categories of this paper are: comp-gas
4
The categories of this paper are: cond-mat
13
The categories of this paper are: quant-ph
26
The categories of this paper are: bayes-an
8
The categories of this paper are: hep-ex