Transport Coefficients of Hadronic Matter NearTc

Abstract

A hadron resonance gas model including all known particles and resonances with masses m < 2 GeV and an exponentially rising density of Hagedorn states for m > 2 GeV is used to obtain an upper bound on the shear viscosity to entropy density ratio, eta/s approximately 1/(4pi), of hadronic matter near Tc. We found a large trace anomaly and small speed of sound near Tc, which agree well with recent lattice calculations. We comment on the bulk viscosity to entropy density ratio close to Tc.

Shear and bulk viscosities of the gluon plasma in a quasiparticle description

“…This, however, seems to be unfavored by recent results obtained for T T c in the confined phase [118][119][120].…”

“…In fact, the observed possible rapid increase of η/s with decreasing T close to T c as well as the behavior with T in the confined phase [118][119][120] call for refinements in viscous hydrodynamic simulations [133][134][135]. The smallness of ζ /s over a wide range of T , in contrast, could suggest that the impact of bulk viscous effects is less important.…”

Event-by-EventHydrodynamics+JetEnergy Loss: A Solution to theRAA⊗vNoronha-Hostler1, Betz2, Noronha3 et al. 2016Phys. Rev. Lett.Self Cite11761573View full textAdd to dashboardCite

“…Information about four transport coe cients is required: the temperature-dependent shear and bulk viscosities, ⌘ and ⇣, and their respective relaxation time coe cients, ⌧ ⇡ and ⌧ ⇧ (other 2nd order transport coe cients [71] are not yet taken into account). For simplicity, e↵ects from the temperature dependence of ⌘/s in the hadronic [72][73][74] or in the QGP phase [75] are neglected here and, thus, we set ⌘/s to be a constant. Also, in this first study bulk viscosity [61,62,76] is set to zero.…”

Nonlinear waves in second order conformal hydrodynamics

“…The RPM method described in section B, subsection 1 is used in the simplest conformal relativistic Israel-Stewart hydrodynamics equations (2), (3) and (4).…”

“…In contrast, at low temperatures and nonzero baryon chemical potentials in the hadron gas phase, viscous effects may be considerably more pronounced [4][5][6][7][8]. Numerical studies of the hydrodynamical evolution of the QuarkGluon Plasma (QGP) show that viscosity produces some visible but not very large effects on global observables [9].…”