Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Quasi Periodic Oscillations of Test Particles and Red-Blue Shifts of the
  Photons Emitted By the Charged Test Particles Orbiting the Charged Black Hole
  in the Presence of Quintessence and Clouds of Strings   Here we examine the circular motion of test particles and photons in the
spacetime geometry of charged black hole surrounded by quintessence and clouds
of strings for the equation of state parameter $\omega_q=-2/3$. We observe that
there exist stable circular orbits in this geometry for very small values of
the quintessence and string cloud parameters, i.e., $0<\gamma<<1$ and
$0<\alpha<<1$. We observe that if the values of $\gamma$ and $\alpha$ increase,
the test particle can more easily escape the gravitational field of the black
hole. While the effect of the charge $Q$ of the black hole on the effective
potential is just opposite to that of the $\gamma$ and $\alpha$. Further, we
investigate the quasi-periodic oscillations of test particles near the stable
circular orbits. With the increasing values of $Q$, the stable circular orbits
get away from the central object; therefore, one can observe lower epicyclic
frequencies away from the central gravitating source with the increase in the
values of $Q$. The redshift parameter $z$ of the photons emitted by the charged
test particles moving in the stable circular orbits around the central source
increases with an increase in the parameter $\alpha$ and decreases with an
increase in the values of the charge $Q$. In the Banados-Silk-West (BSW)
process study, we note that the centre of mass-energy at the horizon of this
Riessner-Nordstrom black hole with quintessence and string clouds increases
indefinitely if the charge of one of the colliding particles attains its
critical value. For a better understanding of the study, we show the dependence
of the radii of the circular orbits, energy and angular momentum of the
particles, effective potential, effective force, quasi-periodic oscillations
and red-blue shifts of photons of the test particles in the circular orbits on
the parameters $\alpha$, $\gamma$ and $Q$ graphically.

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The categories of this paper are: hep-ex
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The categories of this paper are: eess
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The categories of this paper are: patt-sol
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The categories of this paper are: physics
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The categories of this paper are: hep-lat
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The categories of this paper are: astro-ph
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The categories of this paper are: quant-ph
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The categories of this paper are: nucl-th
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The categories of this paper are: math-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: cmp-lg
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The categories of this paper are: acc-phys
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The categories of this paper are: atom-ph
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The categories of this paper are: cond-mat
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The categories of this paper are: stat
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The categories of this paper are: q-alg