Pure Lattice Gauge Theory in the Expanding Universe

Using Monte Carlo methods, I study the thermodynamic properties of Z_2 Abelian lattice gauge theory in flat, homogeneous, isotropic, expanding spacetimes characterized by the scale factor a(t). The presence of the scale factor introduces a spacelike domain wall inside the four dimensional spacetime lattice where the phase transition associated with deconfinement occurs. The resulting theory appears identical to introducing a time-dependent effective coupling beta_eff, and could serve as a simple model for the electroweak phase transition of the early Universe.