Cluster growth and dynamic scaling in a two-lane driven diffusive system

Using high precision Monte Carlo simulations and a mean-field theory, we explore coarsening phenomena in a simple driven diffusive system. The model is reminiscent of vehicular traffic on a two-lane ring road. At sufficiently high density, the system develops jams (clusters) which coarsen with time. A key parameter is the passing probability, $\gamma$. For small values of $\gamma$, the growing clusters display dynamic scaling, with a growth exponent of 2/3. For larger values of $\gamma$, the growth exponent must be adjusted, suggesting the ordered (jammed) state is not a genuine phase but rather a finite size effect.