  Driven surface diffusion occurs, for example, in molecular beam epitaxy when
particles are deposited under an oblique angle. Elastic phase transitions
happen when normal modes in crystals become soft due to the vanishing of
certain elastic constants. We show that these seemingly entirely disparate
systems fall under appropriate conditions into the same universality class. We
derive the field theoretic Hamiltonian for this universality class, and we use
renormalized field theory to calculate critical exponents and logarithmic
corrections for several experimentally relevant quantities.
