Patterns from Preheating

The formation of regular patterns is a well-known phenomenon in condensed matter physics. Systems that exhibit pattern formation are typically driven and dissipative with pattern formation occurring in the weakly nonlinear regime and sometimes even in more strongly nonlinear regions of parameter space. In the early universe, parametric resonance can drive explosive particle production called preheating. The fields that are populated then decay quantum mechanically if their particles are unstable. Thus, during preheating, a driven-dissipative system exists. Motivated by the application to cosmology, we present a case study for pattern formation in relativistic nonlinear wave equations.