977 research outputs found
Non-perturbative Approach to Equation of State and Collective Modes of the QGP
We discuss a non-perturbative -matrix approach to investigate the
microscopic structure of the quark-gluon plasma (QGP). Utilizing an effective
Hamiltonian which includes both light- and heavy-parton degrees of freedoms.
The basic two-body interaction includes color-Coulomb and confining
contributions in all available color channels, and is constrained by
lattice-QCD data for the heavy-quark free energy. The in-medium -matrices
and parton spectral functions are computed selfconsistently with full account
of off-shell properties encoded in large scattering widths. We apply the
-matrices to calculate the equation of state (EoS) for the QGP, including a
ladder resummation of the Luttinger-Ward functional using a matrix-log
technique to account for the dynamical formation of bound states. It turns out
that the latter become the dominant degrees of freedom in the EoS at low QGP
temperatures indicating a transition from parton to hadron degrees of freedom.
The calculated spectral properties of one- and two-body states confirm this
picture, where large parton scattering rates dissolve the parton quasiparticle
structures while broad resonances start to form as the pseudocritical
temperature is approached from above. Further calculations of transport
coefficients reveal a small viscosity and heavy-quark diffusion coefficient.Comment: 10 pages, 8 figures, proceedings of XLVII International Symposium on
Multiparticle Dynamics (ISMD2017
Heavy-Light Susceptibilities in a Strongly Coupled Quark-Gluon Plasma
Quark number susceptibilities as computed in lattice QCD are commonly
believed to provide insights into the microscopic structure of QCD matter, in
particular its degrees of freedom. We generalize a previously constructed
partonic -matrix approach to finite chemical potential to calculate various
susceptibilities, in particular for configurations containing a heavy charm
quark. At vanishing chemical potential and moderate temperatures, this approach
predicts large collisional widths of partons generated by dynamically formed
hadronic resonance states which lead to transport parameters characteristic for
a strongly coupled system. The quark chemical potential dependence is
implemented into the propagators and the in-medium color potential, where two
newly introduced parameters for the thermal and screening masses are fixed
through a fit to the baryon number susceptibility, . With this setup,
we calculate heavy-light susceptibilities without further tuning; the results
qualitatively agree with the lattice-QCD (lQCD) data for both
and . This implies that the lQCD results are compatible with a
significant content of broad -meson and charm-light diquark bound states in
a moderately hot QGP.Comment: 6 pages, 4 figure
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