Critical phenomena of RNA-like polymers -- a synopsis

This work examines field theories for RNA-like polymers with single strand and double strand polymers and a periodic base sequence. These field theories originate from lattice models, describe polymers in a good solvent, and in principle exactly describe the critical behavior. A central role is played by the conventional one-component branched polymer and the mapping of the corresponding field theory to the Lee-Yang field theory in two less dimensions. Critical phenomena in the context of polymers as well as the Lee-Yang model entail pecularities, which we derive in detail. A new result is that the critical point of RNA-like branched polymers (with periodic base sequence) looks like the critical point of the classical one-component branched polymer, but with one more critical exponent for the single strand polymer. A random base sequence generates additional relevant interactions, and invalidates the simple picture.