Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Model of the gravitational dipole   A model of the gravitational dipole is proposed in a close analogy to that of
the global monopole. The physical properties and the range of validity of the
model are examined as is the motion of test particles in the dipole background.
It is found that the metric of the gravitational dipole describes a curved
space-time, so one would expect it to have a more pronounced effect on the
motion of the test particles than the spinning cosmic string. It is indeed so
and in the generic case the impact of repulsive centrifugal force results in a
motion whose orbits when projected on the equatorial plane represent unfolding
spirals or hyperbolas. Only in one special case these projections are straight
lines, pretty much in a manner observed in the field of the spinning cosmic
string. Even if open, the orbits are nevertheless bounded in the angular
coordinate $\theta$.

35
The categories of this paper are: mtrl-th
2
The categories of this paper are: math
23
The categories of this paper are: solv-int
32
The categories of this paper are: atom-ph
13
The categories of this paper are: quant-ph
18
The categories of this paper are: econ
33
The categories of this paper are: plasm-ph
17
The categories of this paper are: q-fin
1
The categories of this paper are: cs
27
The categories of this paper are: comp-gas
28
The categories of this paper are: alg-geom
21
The categories of this paper are: adap-org
0
The categories of this paper are: hep-ph
25
The categories of this paper are: patt-sol
12
The categories of this paper are: nucl-th
9
The categories of this paper are: nlin