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Centro de Astrofísica da Universidade do Porto
22-26 August 2011, Porto, Portugal

 

"Modeling Phase Transitions in Dynamical Environments"
Yueker, Daniel (Frankfurt Institute for Advanced Studies (FIAS))

An interesting way of testing the standard model is to look for possible consequences of predicted phase transitions in the early universe. Particularly, electro-weak and deconfinement/chiral phase transitions are often discussed in this context. Even stronger dynamical effects are expected in the fireballs created in relativistic heavy-ion collisions. Because of the fast expansion one should expect non-equilibrium effects, such as nucleation, spinodal decomposition, supercooling and reheating, to be important. Due to theoretical uncertainties, we consider different possibilities regarding the type of a phase transition, the mechanism of the phase transformation and dynamics of the expansion. Since the early universe is almost baryon-antibaryon symmetric, its baryochemical potential is close to zero. As well established by lattice calculations, in this case the deconfinement phase transition occurs at a temperature below 200 MeV at time of 10-5 seconds after the big bang. We use an effective field-theoretical model to describe the QCD phase transition for different expansion rates. It is assumed that the formation of a new phase proceeds via thermal fluctuations. For the case of cosmological expansion a iterative scheme is formulated where the Hubble parameter is determined self-consistently with the order parameter. A possibility of "small inflation" scenario is discussed.