arXiv subjects

Shuai Y. F. Liu

Publications and source records attributed to Shuai Y. F. Liu.

21 records · Page 2Linked to original sources

arXiv2017

Non-perturbative Approach to Equation of State and Collective Modes of the QGP

We discuss a non-perturbative $T$-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 $T$-matrices and parton spectral functions are computed selfconsistently with full account of off-shell properties encoded in large scattering widths. We apply the $T$-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.

nucl-th↗

arXiv2016

$T$-Matrix Approach to Strongly Coupled QGP

Based on a thermodynamic $T$-matrix approach we extract the potential $V$ between two static charges in the quark-gluon plasma (QGP) from fits to the pertinent lattice-QCD free energy. With suitable relativistic corrections we utilize this new potential to compute heavy-quark transport coefficients and compare the results to previous calculations using either $F$ or $U$ as potential. We then discuss a generalization of the $T$-matrix re-summation to a "matrix $\log$" re-summation of $t$-channel diagrams for the grand partition function of the QGP in the Luttinger-Ward skeleton diagram formalism. With $V$ as a non-perturbative driving kernel in the light-parton sector, we obtain the QGP equation of state from fits to lattice-QCD data. The resulting light-parton spectral functions are characterized by large thermal widths at small momenta, indicating the dissolution of quasi-particles in a strongly coupled QGP.

hep-ph↗

arXiv2015

An in-Medium Heavy-Quark Potential from the $Q\bar{Q}$ Free Energy

We investigate the problem of extracting a static potential between a quark and its antiquark in a quark-gluon plasma (QGP) from lattice-QCD computations of the singlet free energy, $F_{Q\bar{Q}}(r)$. We utilize the thermodynamic $T$-matrix formalism to calculate the free energy from an underlying potential ansatz resummed in ladder approximation. Imaginary parts of both $Q\bar Q$ potential-type and single-quark selfenergies are included as estimated from earlier results of the $T$-matrix approach. We find that the imaginary parts, and in particular their (low-) energy dependence, induce marked deviations of the (real part of the) potential from the calculated free energy. When fitting lattice results of the latter, the extracted potential is characterized by significant long-range contributions from remnants of the confining force. We briefly discuss consequences of this feature for the heavy-quark transport coefficient in the QGP.

hep-ph↗