V. Guttal and R. Bundschuh, Phys. Rev. Lett. 96 (2005) 018105/1--018105/4
We study the statistical mechanics of RNA secondary structures designed to have an attraction between two different types of structures as a model system for heteropolymer aggregation. The competition between the branching entropy of the secondary structure and the energy gained by pairing drives the RNA to undergo a `temperature independent' second order phase transition from a molten to an aggregated phase. The aggregated phase thus obtained has a macroscopically large number of contacts between different RNAs. The partition function scaling exponent for this phase is θ≅ 1/2 and the crossover exponent of the phase transition is ν≅5/3.