Viscous QCD matter in a hybrid hydrodynamic+Boltzmann approach

By Huichao Song, Steffen A. Bass, Ulrich Heinz. 2010

132 citations recorded by the source corpus.

A hybrid transport approach for the bulk evolution of viscous QCD matter produced in ultrarelativistic heavy-ion collisions is presented. The expansion of the dense deconfined phase of the reaction is modeled with viscous hydrodynamics while the dilute late hadron gas stage is described microscopically by the Boltzmann equation. The advantages of such a hybrid approach lie in the improved capability of handling large dissipative corrections in the late dilute phase of the reaction, including a realistic treatment of the non-equilibrium hadronic chemistry and kinetic freeze-out. By varying the switching temperature at which the hydrodynamic output is converted to particles for further propagation with the Boltzmann cascade we test the ability of the macroscopic hydrodynamic approach to emulate the microscopic evolution during the hadronic stage and extract the temperature dependence of the effective shear viscosity of the hadron resonance gas produced in the collision. We find that the extracted values depend on the prior hydrodynamic history and hence do not represent fundamental transport properties of the hadron resonance gas. We conclude that viscous fluid dynamics does not provide a faithful description of hadron resonance gas dynamics with predictive power, and that both components of the hybrid approach are needed for a quantitative description of the fireball expansion and its freeze-out.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/5470f271d63162a93b63d305c4f5b8c6ee32e104

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In Astronomy and Astrophysics

1. K. Gajdošová
2. You Zhou
3. Huichao Song
4. A. Jaiswal
5. Zhi Qiu
6. Chun Shen
7. Ulrich Heinz
8. V. Roy

In Nuclear and High Energy Physics

1. Huichao Song
2. K. Gajdošová
3. You Zhou
4. Chun Shen
5. Jonah E. Bernhard
6. Steffen A. Bass
7. Zhi Qiu
8. Ulrich Heinz

Citations in the corpus

• Relativistic Hydrodynamics in Heavy-Ion Collisions: General Aspects and Recent Developments (2016, background): “One of the first numerical code VISHNU that couples (2+1)D viscous hydro with a late hadronic Boltzmann cascade appeared in 2011 [155].”
• The iEBE-VISHNU code package for relativistic heavy-ion collisions (2014, methodology): “and (if unstable) decay.3 The combination of the hydrodynamic evolution algorithm for the QGP stage with a microscopic hadronic cascade forms a hybrid algorithm with the name VISHNU(VISH2+1’n’ UrQMD) [36]. In the end, we collect the final particle information (momenta and positions of their last inte”
• Collective flow and hydrodynamics in large and small systems at the LHC (2017, methodology): “For a realistic description of the evolution and decoupling of the hadronic matter, the OSU-LBL group further developed the VISHNU hybrid model [121] which combines the 2?1-d viscous hydrodynamics with a hadron cascade model-UrQMD and then made a semi-qualitative extraction of the QGP shear viscosit”