The quark-hadron transition and hot hadronic matter in the early universe

Various calculations· of the evolution of the hadron gas in the early universe are carried out. To determine the starting point for the evolution equations a phase transition between the quark-gluon plasma phase and the hadron gas phase is constructed. A simple calculation leads to an estimate of the chemical potential of baryons at the quark-hadron phase transition in the early universe. We investigate how the transition temperature depends on the equations of state for the bagged quark and the hadron phase. A particle density evolution model is introduced which predicts the temperature at which particle species drop out of equilibrium (freeze-out) in an expanding universe. We then construct dynamical evolution equations to describe the reactions of interacting pions and photons. In order to model a more realistic hadron gas, we include kaons and finally nucleons and hyperons into the model universe. The results indicate that this type of model should be extended to include more interacting particle species and that a more realistic evolution model is dependent on obtaining accurate reaction cross-sections.

Grantor dc:publisher.institution

Department of Physics

Year dc:date.issued

1987

Author dc:creator

• Von Oertzen, Detlof Wilhelm

Advisors dc:contributor.advisor

• Rafelski, Johann
• Cleymans, Jean

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/15904

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/15904