Nuclear Physics & RIKEN Theory Seminar

"Eta/s of a relativistic hadron gas from a hadronic cascade"

Presented by Nasser Demir, Duke University

Friday, June 5, 2009, 2:00 pm — Small Seminar Room, Bldg. 510

Ultrarelativistic heavy-ion collisions at the Brookhaven National Laboratory Relativistic Heavy Ion Collider (RHIC) are thought to have produced a state of matter called the quark-gluon plasma, characterized by a very small shear-viscosity to entropy-density ratio eta/s, near the lower bound predicted for that quantity by the KSS bound. As the produced matter expands and cools, it evolves through a phase described by a hadron gas with rapidly increasing eta/s. We present a calculation of eta/s as a function of temperature utilizing the Ultrarelativistic Quantum Molecular Dynamics (UrQMD) model, and investigate the effect of the separation of thermal vs chemical freezeout on eta/s in our calculation. Our results find that eta/s in the hadronic phase is rather large, and the oft-discussed viscous hydrodynamics calculations suggest a strong temperature dependence of eta/s, especially as it crosses T_c in a heavy ion reaction.

Hosted by: Gregory Soyez

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