Secondary bifurcations and symmetry breaking as a route towards spatiotemporal disorder

We analyse an equation describing long-wavelength transverse instabilities of a roll-like periodic pattern that has solutions which undergo a series of transitions between states with different symmetries as the order parameter is changed. The transitions appear when the solutions are already chaotic and so are not bifurcations of the usual type. We investigate the first of these transitions in detail, and relate the results to those of a simple low order truncation of the governing p.d.e.’s.