Deconfinement transition dynamics and early thermalization in QGP

We perform SU(3) Lattice Gauge Theory simulations of the deconfinement transition attempting to mimic conditions encountered in heavy ion collisions. Specifically, we perform a sudden temperature quench across the deconfinement temperature, and follow the response of the system in successive simulation sweeps under spatial lattice expansion and temperature fall-off. In measurements of the Polyakov loop and structure functions a robust strong signal of global instability response is observed through the exponential growth of low momentum modes. Development of these long range modes isotropizes the system which reaches thermalization shortly afterwards, and enters a stage of quasi-equilibrium expansion and cooling till its return to the confinement phase. The time scale characterizing full growth of the long range modes is largely unaffected by the conditions of spatial expansion and temperature variation in the system, and is much shorter than the scale set by the interval to return to the confinement phase. The wide separation of these two scales is such that it naturally results in isotropization times well inside 1 fm/c.Comment: 11 pages, 8 eps figures, added references, typos correcte

Phase Behavior of Short Range Square Well Model

Various Monte Carlo techniques are used to determine the complete phase diagrams of the square well model for the attractive ranges $\lambda = 1.15$ and $\lambda = 1.25$. The results for the latter case are in agreement with earlier Monte Carlo simulations for the fluid-fluid coexistence curve and yield new results for the liquidus-solidus lines. Our results for $\lambda = 1.15$ are new. We find that the fluid-fluid critical point is metastable for both cases, with the case $\lambda = 1.25$ being just below the threshold value for metastability. We compare our results with prior studies and with experimental results for the gamma-II crystallin.Comment: 8 figures, 1 tabl

Nucleation theory and the phase diagram of the magnetization-reversal transition

The phase diagram of the dynamic magnetization-reversal transition in pure Ising systems under a pulsed field competing with the existing order can be explained satisfactorily using the classical nucleation theory. Indications of single-domain and multi-domain nucleation and of the corresponding changes in the nucleation rates are clearly observed. The nature of the second time scale of relaxation, apart from the field driven nucleation time, and the origin of its unusual large values at the phase boundary are explained from the disappearing tendency of kinks on the domain wall surfaces after the withdrawal of the pulse. The possibility of scaling behaviour in the multi-domain regime is identified and compared with the earlier observations.Comment: 10 pages Latex, 4 Postscript figure

Ion specific effects on phase transitions in protein solutions

A recent Monte Carlo simulation determined the potential of mean force between two lysozyme molecules in various aqueous solutions [M. Lund et al. Phys. Rev. Lett. 100, 258105 (2008)]. The study involved a combination of explicit solvent and continuum model simulations and showed that there are significant ion-specific protein-protein interactions due to hydrophobic patches on the protein surfaces. In this paper we use the results of their study to determine the phase diagram for lysozyme for aqueous solutions of NaCl and NaI. Two of the three phase diagrams have a stable fluid-fluid critical point, while the third has a slightly metastable critical point. This results from a secondary extremum in the potential associated with a repulsive interaction. This repulsive interaction reduces the effective range of the attractive interaction and produces a metastable critical point. We compare the results of one of these phase diagrams with that for a model that includes ion-dispersion forces, but does not contain solvent structural effects.Comment: 9 figure files + 1 tex fil