Shear viscosity of a hadron gas and influence of resonance lifetimes on relaxation time

Abstract

We address a discrepancy between different computations of $\eta /s$ (shear viscosity over entropy density) of hadronic matter. Substantial deviations of this coefficient are found between transport approaches mainly based on resonance propagation with finite lifetime and other (semi-analytical) approaches with energy-dependent cross-sections, where interactions do not introduce a timescale. We provide an independent extraction of this coefficient by using the newly-developed SMASH (Simulating Many Accelerated Strongly interacting Hadrons) transport code, which is an example of a mainly resonance-based approach. We compare the results from SMASH with numerical solutions of the Boltzmann equation for simple systems using the Chapman-Enskog expansion, as well as previous results in the literature. Our conclusion is that the hadron interaction via resonance formation/decay strongly affects the transport properties of the system, resulting in significant differences in $\eta /s$ with respect to other approaches where binary collisions dominate. We argue that the relaxation time of the system ---which characterizes the shear viscosity--- is determined by the interplay between the mean-free time and the lifetime of resonances. We show how an artificial shortening of the resonance lifetimes, or the addition of a background elastic cross section nicely interpolate between the two discrepant results.

15 pages, 16 figures

References in corpus (13)

• Viscosity in Strongly Interacting Quantum Field Theories from Black Hole Physics
• The order of the quantum chromodynamics transition predicted by the standard model of particle physics
• Viscosity Information from Relativistic Nuclear Collisions: How Perfect is the Fluid Observed at RHIC?
• On the Strongly-Interacting Low-Viscosity Matter Created in Relativistic Nuclear Collisions
• Transport coefficients for bulk viscous evolution in the relaxation time approximation
• Dynamical vs. equilibrium properties of the QCD phase transition: a holographic perspective
• Temperature dependence of shear viscosity of $SU(3)$--gluodynamics within lattice simulation
• Shear viscosity of a hadronic gas mixture
• Shear Viscosity to Entropy Density Ratio of QCD below the Deconfinement Temperature
• Investigating the collision energy dependence of $\eta$/s in RHIC beam energy scan using Bayesian statistics
• Phase Transitions and the Perfectness of Fluids
• $\eta /s$ and Phase Transitions
• Determining Transport Coefficients for a Microscopic Simulation of a Hadron Gas

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