Smectic-A-smectic-C phase transition in biaxial disordered environments.

We study the smectic-A-smectic-C phase transition in biaxial disordered environments, e.g., fully anisotropic aerogel. We find that both the A and C phases belong to the universality class of the "XY Bragg glass," and therefore have quasi-long-ranged translational smectic order. The phase transition itself belongs to a new universality class, which we study using an ε=7/2-d expansion. We find a stable fixed point, which implies a continuous transition, the critical exponents of which we calculate.