Shear Viscosity from Lattice QCD

Mages, Simon; Szabó, Kornélia; Schäfer, Andreas; Borsányi, Szabolcs; Fodor, Z.

doi:10.22323/1.214.0232

Cited by 31 publications

(44 citation statements)

References 14 publications

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“…This would suggest that viscosities in the QGP approach that of a hadron gas for temperatures in the transition region, and would also be similar to values from recent lattice calculations [11], which also have rather high uncertainties. Perturbation theory does predict significantly higher viscosities [13], which suggests that the non-perturbative nature of QCD matter continues for energy densities significantly higher than the transition region, 150 < ∼ T < ∼ 220 MeV.…”

Section: Discussionsupporting

confidence: 78%

“…As such, inferring properties of the quarkgluon plasma phase from the measured particle spectra and correlations with good precision naturally requires a solid understanding of the properties of the hadron resonance gas. Lattice gauge theory has provided estimates of the viscosity for pure gauge theory [9][10][11][12], but the uncertainty of such estimates are difficult to quantify due to the analytic continuation of correlations in imaginary time, which are readily extracted from lattice calculations, to real time, which are what is needed for the Kubo relation that gives the viscosity. Perturbative QCD also provides estimates of the viscosity [13], but such calculations can be questionable for lower temperatures near the phase transition.…”

Section: Introductionmentioning

confidence: 99%

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Determining transport coefficients for a microscopic simulation of a hadron gas

2017

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Quark-Gluon plasmas produced in relativistic heavy-ion collisions quickly expand and cool, entering a phase consisting of multiple interacting hadronic resonances just below the QCD deconfinement temperature, T ∼ 155 MeV. Numerical microscopic simulations have emerged as the principal method for modeling the behavior of the hadronic stage of heavy-ion collisions, but the transport properties that characterize these simulations are not well understood. Methods are presented here for extracting the shear viscosity, and two transport parameters that emerge in Israel-Stewart hydrodynamics. The analysis is based on studying how the stress-energy tensor responds to velocity gradients. Results are consistent with Kubo relations if viscous relaxation times are twice the collision time.

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Section: Discussionsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Determining transport coefficients for a microscopic simulation of a hadron gas

2017

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“…For computations based on lattice simulations see e.g. [6][7][8][9][10][11][12][13]60]. On the other hand such real-time properties can also be accessed via the spectral functions of the fundamental constituents of QCD, gluons and quarks; see e.g.…”

Section: Introductionmentioning

confidence: 99%

Finite-temperature gluon spectral functions from $$N_f=2+1+1$$ N f = 2 + 1 + 1 lattice

et al. 2018

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We investigate gluon correlation functions and spectral functions at finite temperature in Landau gauge on lattice QCD ensembles with N f = 2 + 1 + 1 dynamical twisted-mass quarks flavors, generated by the tmfT collaboration. They cover a temperature range from 0.8 ≤ T /T C ≤ 4 using the fixed-scale approach. Our study of spectral properties is based on a novel Bayesian approach for the extraction of non-positive-definite spectral functions. For each binned spatial momentum we take into account the gluon correlation functions at all available discrete imaginary frequencies. Clear indications for the existence of a well defined quasiparticle peak are obtained. Due to a relatively small number of imaginary frequencies available, we focus on the momentum and temperature dependence of the position of this spectral feature. The corresponding dispersion relation reveals different in-medium masses for longitudinal and transversal gluons at high temperatures, qualitatively consistent with weak coupling expectations.

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“…There were only few attempts to calculate shear viscosity of SU(3)-gluodynamics [9][10][11][12][13] and SU(2)-gluodynamics [14,15]. In this paper we are going to study temperature dependence of shear viscosity of SU(3)-gluodynamics in the vicinity of confinement/deconfinement phase transition T/T c ∈ [0.9, 1.5].…”

Section: Introductionmentioning

confidence: 99%

Temperature dependence of shear viscosity ofSU(3)-gluodynamics within lattice simulation

2017

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Abstract. This report is devoted to the study of temperature dependence of shear viscosity in S U(3)-gluodynamics. To calculate shear viscosity we measured the correlation function of the energy-momentum tensor T 12 T 12 for a set of temperatures in the region T/T c ∈ (0.9, 1.5). The measurements were carried out using multilevel algorithm which considerably improves the accuracy of the data. For determination of the shear viscosity two methods were used: physically motivated ansatz and non-parametrical BackusGilbert method. Both methods give consistent results. The calculation allows to determine temperature dependence of the ratio of shear viscosity to the entropy density η/s.

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Shear Viscosity from Lattice QCD

Cited by 31 publications

References 14 publications

Determining transport coefficients for a microscopic simulation of a hadron gas

Determining transport coefficients for a microscopic simulation of a hadron gas

Finite-temperature gluon spectral functions from $$N_f=2+1+1$$ N f = 2 + 1 + 1 lattice

Temperature dependence of shear viscosity ofSU(3)-gluodynamics within lattice simulation

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