University of Minnesota
School of Physics & Astronomy

Physics and Astronomy Calendar

Monday, November 23rd 2015
4:00 pm:
Thesis Defense in 434 PAN
Speaker: Michael Albright, University of Minnesota
Subject: Thermodynamics of Hot Hadronic Gases at Finite Baryon Densities
This is the public portion of Mr. Albright's thesis defense. His advisor is Joseph Kapusta

The universe is filled with protons and neutrons, which are themselves made of quarks and gluons. However, microseconds after the Big Bang, the universe was so hot and dense that quarks and gluons existed in other phases--first as a quark-gluon plasma, then as a hadron gas. Remarkably, these exotic phases of matter are created and studied experimentally in heavy-ion collisions at particle accelerators like RHIC at Brookhaven National Lab and the LHC at CERN. There is a strong effort underway to develop precision models of heavy-ion collisions which, combined with experimental data, will enable improved determination of many physical properties of quark-gluon matter. Recent years have seen significant improvements in modeling matter with zero net baryon density, which is relevant for RHIC, the LHC, and the early universe. However, there is growing interest in matter with a large net baryon density, which is relevant for neutron stars and future collider experiments. Hence, in this thesis we compute various thermodynamic properties of matter at large baryon densities. We first improve the popular hadron resonance gas equation of state (EoS) by including repulsive interactions, which are important at large baryon densities. Next, we develop crossover equations of state which smoothly transition from hadron gas models at low energy densities to a quark-gluon plasma EoS at high energy densities. We then compute net baryon number fluctuations and compare them to measurements from the STAR Collaboration at RHIC. We find that fluctuations freeze out long after chemical reactions do. Finally we develop a relativistic quasiparticle kinetic theory of hadron gases at large baryon densities. This includes interactions via scalar and vector mean fields in a thermodynamically consistent way. We then derive formulas for the shear and bulk viscosity and thermal conductivity, which are interesting quantities that influence experimental observables.

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