Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Measuring gravitational effects on antimatter in space   We propose an experimental test of the gravitational interaction with
antimatter by measuring the branching fraction of the CP~violating decay
$K_\mathrm{L} \to \pi^{+} \pi^{-}$ in space. We show that at the altitude of
the International Space Station, gravitational effects may change the level of
CP~violation such that a 5$\sigma$ discrimination may be obtained by collecting
the $K_\mathrm{L}$ produced by the cosmic proton flux within a few years.

21
The categories of this paper are: adap-org
19
The categories of this paper are: eess
16
The categories of this paper are: stat
27
The categories of this paper are: comp-gas
20
The categories of this paper are: acc-phys
11
The categories of this paper are: hep-lat
35
The categories of this paper are: mtrl-th
1
The categories of this paper are: cs
37
The categories of this paper are: supr-con
22
The categories of this paper are: chao-dyn
33
The categories of this paper are: plasm-ph
4
The categories of this paper are: cond-mat
29
The categories of this paper are: funct-an
24
The categories of this paper are: dg-ga
31
The categories of this paper are: ao-sci
14
The categories of this paper are: math-ph