Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Gauge-invariant screening masses and static quark free energies in $N_f
  = 2+1$ QCD at non-zero baryon density   We discuss the extension of gauge-invariant electric and magnetic screening
masses in the Quark-Gluon Plasma to the case of a finite baryon density,
defining them in terms of a matrix of Polyakov loop correlators. We present
lattice results for $N_f=2+1$ QCD with physical quark masses, obtained using
the imaginary chemical potential approach, which indicate that the screening
masses increase as a function of $\mu_B$. A separate analysis is carried out
for the theoretically interesting case $\mu_B/T=3 i \pi$, where charge
conjugation is not explicitly broken and the usual definition of the screening
masses can be used for temperatures below the Roberge-Weiss transition.
Finally, we investigate the dependence of the static quark free energy on the
baryon chemical potential, showing that it is a decreasing function of $\mu_B$
which displays a peculiar behavior as the pseudocritical transition temperature
at $\mu_B=0$ is approached.

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The categories of this paper are: nucl-th
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The categories of this paper are: quant-ph
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The categories of this paper are: dg-ga
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The categories of this paper are: econ
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The categories of this paper are: plasm-ph
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The categories of this paper are: chem-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: eess
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The categories of this paper are: hep-ex
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The categories of this paper are: astro-ph
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The categories of this paper are: chao-dyn
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The categories of this paper are: math-ph
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The categories of this paper are: patt-sol
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The categories of this paper are: comp-gas
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The categories of this paper are: q-fin