Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Collisional processes of on-shell and off-shell heavy quarks in vacuum
  and in the Quark-Gluon-Plasma   We study the heavy quark scattering on partons of the quark gluon plasma
(QGP) being especially interested in the collisional (elastic) scattering
processes of heavy quarks on quarks and gluons. We calculate the different
cross sections for perturbative partons (massless on-shell particles in the
vacuum) and for dynamical quasi-particles (off-shell particles in the QGP
medium as described by the dynamical quasi-particles model "DQPM") using the
leading order Born diagrams. Our results show clearly the effect of a finite
parton mass and width on the perturbative elastic $(q(g) Q \rightarrow q (g)
Q)$ cross sections which depend on temperature $T$, energy density $\epsilon$,
the invariant energy $\sqrt{s}$ and the scattering angle $\theta$. Our detailed
comparisons demonstrate that the finite width of the quasi-particles in the
DQPM - which encodes the multiple partonic scattering - has little influence on
the cross section for $q Q \rightarrow q Q$ as well as $g Q \rightarrow g Q$
scattering except close to thresholds. Thus when studying the dynamics of
energetic heavy quarks in a QGP medium the spectral width of the
degrees-of-freedom may be discarded. We have, furthermore, compared the cross
sections from the DQPM with corresponding results from hard-thermal-loop (HTL)
approaches. The HTL inspired models - essentially fixing the regulators by
elementary vacuum cross sections and decay amplitudes instead of properties of
the QGP at finite temperature - provide quite different results especially
w.r.t. the temperature dependence of the $qQ$ and $gQ$ cross sections (in all
settings). Accordingly, the transport properties of heavy quarks will be very
different as a function of temperature when compared to DQPM results.

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The categories of this paper are: econ
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The categories of this paper are: q-fin
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The categories of this paper are: nlin
5
The categories of this paper are: gr-qc
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The categories of this paper are: comp-gas
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The categories of this paper are: math
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The categories of this paper are: hep-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: atom-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: cond-mat
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The categories of this paper are: mtrl-th
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The categories of this paper are: math-ph
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The categories of this paper are: ao-sci
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The categories of this paper are: cmp-lg
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The categories of this paper are: physics