CRITICAL-POINTS IN LAYERED SYSTEMS

Critical points that do not involve any symmetry change are shown to define a set of new universality classes in layered systems. Extension of this problem to higher dimensions may be made in an infinite number of ways which define continuously varying upper critical dimensions. This allows us to estimate uncertainties on the critical-exponent values obtained in a first-order Wilson expansion. The corresponding physical situations include the electric field induced chiral-smectic-C -chiral-smectic-C critical point, the smectic-A-smectic-A critical point, but also the smectic-C-smectic-I and smectic-C-smectic-F critical points which have not been discovered experimentally yet. Recent experiments provide encouraging support to the current analysis.