Inclusive and effective bulk viscosities in the hadron gas

  • We estimate the temperature dependence of the bulk viscosity in a relativistic hadron gas. Employing the Green–Kubo formalism in the SMASH (Simulating Many Accelerated Strongly-interacting Hadrons) transport approach, we study different hadronic systems in increasing order of complexity. We analyze the (in)validity of the single exponential relaxation ansatz for the bulk-channel correlation function and the strong influence of the resonances and their lifetimes. We discuss the difference between the inclusive bulk viscosity of an equilibrated, long-lived system, and the effective bulk viscosity of a short-lived mixture like the hadronic phase of relativistic heavy-ion collisions, where the processes whose inverse relaxation rate are larger than the fireball duration are excluded from the analysis. This clarifies the differences between previous approaches which computed the bulk viscosity including/excluding the very slow processes in the hadron gas. We compare our final results with previous hadron gas calculations and confirm a decreasing trend of the inclusive bulk viscosity over entropy density as temperature increases, whereas the effective bulk viscosity to entropy ratio, while being lower than the inclusive one, shows no strong dependence to temperature.

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Author:Jean-Bernard RoseORCiDGND, Juan M. Torres-RinconORCiDGND, Hannah ElfnerORCiDGND
Parent Title (English):Journal of physics. G
Publisher:IOP Publ.
Place of publication:Bristol
Document Type:Article
Date of Publication (online):2020/12/02
Date of first Publication:2020/12/02
Publishing Institution:Universitätsbibliothek Johann Christian Senckenberg
Release Date:2023/08/02
Tag:Monte-Carlo simulations; bulk viscosity; hadron gas; heavy-ion collisions
Issue:art. 015005
Article Number:015005
Page Number:32
First Page:1
Last Page:31
Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation)—Project number 315477589—TRR 211.
This work was supported by the Helmholtz International Center for the Facility for Antiproton and Ion Research (HIC for FAIR) within the framework of the Landes-Offensive zur Entwicklung Wissenschaftlich-Oekonomischer Exzellenz (LOEWE) program launched by the State of Hesse.
Institutes:Physik / Physik
Wissenschaftliche Zentren und koordinierte Programme / Frankfurt Institute for Advanced Studies (FIAS)
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 53 Physik / 530 Physik
Licence (German):License LogoCreative Commons - CC BY - Namensnennung 4.0 International