Transition between chaotic and stochastic universality classes of kinetic roughening*

The dynamics of non-equilibrium spatially extended systems are often dominated by fluctuations, due to e.g. deterministic chaos or to intrinsic stochasticity. This reflects into kinetic roughening behavior classified into universality classes defined by critical exponent values and by the probability distribution function (PDF) of field fluctuations. Geometrical constraints are known to change secondary features of the PDF while keeping the exponent values unchanged, inducing universality subclasses. Working on the Kuramoto-Sivashinsky equation as a paradigm of spatiotemporal chaos (related with the paramount Burgers and Kardar-Parisi-Zhang equations via large-scale asymptotics [1]), we show [2] that the chaotic or stochastic nature of the prevailing fluctuations can also change the universality class while respecting the exponent values, as the PDF is substantially altered. This transition takes place at a non-zero value of the stochastic noise amplitude and may be suitable for experimental verification.
[1] E. Rodriguez-Fernandez and R. Cuerno, Phys. Rev. E 99, 042108 (2019); 101, 052126 (2020).
[2] E. Rodriguez-Fernandez and R. Cuerno, arXiv:2009.11804 (2020).