Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Periodic orbits around a spherically symmetric naked singularity   The motion of time-like test particles in the Fisher/Janis-Newman-Winicour
(F/JNW) spacetime is studied with the Hamiltonian formulation of the geodesic
equations. The spacetime is characterised by its mass parameter $r_g$ and
scalar field parameter $\nu$. The innermost bound and stable circular orbits
are calculated and the effective potential is analysed. Consistent with
numerical results in earlier literature, for $\nu<1/2$, particles with non-zero
angular momentum encounter an infinite potential barrier, preventing them from
reaching the naked singularity at $r=r_g$. Periodic orbits in the spacetime are
also obtained. Compared to the periodic orbits around the Schwarzschild black
hole, it is found that typically lower energies are required for the same
orbits in the F/JNW spacetime.

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The categories of this paper are: ao-sci
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The categories of this paper are: comp-gas
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The categories of this paper are: chao-dyn
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The categories of this paper are: quant-ph
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The categories of this paper are: astro-ph
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The categories of this paper are: nucl-ex
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The categories of this paper are: math
0
The categories of this paper are: hep-ph
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The categories of this paper are: q-fin
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The categories of this paper are: q-alg
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The categories of this paper are: dg-ga
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The categories of this paper are: hep-lat
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The categories of this paper are: solv-int
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The categories of this paper are: adap-org
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The categories of this paper are: cmp-lg
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The categories of this paper are: eess