513 research outputs found
Multiple Crossover Phenomena and Scale Hopping in Two Dimensions
We study the renormalization group for nearly marginal perturbations of a
minimal conformal field theory M_p with p >> 1. To leading order in
perturbation theory, we find a unique one-parameter family of ``hopping
trajectories'' that is characterized by a staircase-like renormalization group
flow of the C-function and the anomalous dimensions and that is related to a
recently solved factorizable scattering theory. We argue that this system is
described by interactions of the form t phi_{(1,3)} - t' \phi_{(3,1)} . As a
function of the relevant parameter t, it undergoes a phase transition with new
critical exponents simultaneously governed by all fixed points M_p, M_{p-1},
..., M_3. Integrable lattice models represent different phases of the same
integrable system that are distinguished by the sign of the irrelevant
parameter t'.Comment: 20 pages, 5 figure
The Freezing of Random RNA
We study secondary structures of random RNA molecules by means of a
renormalized field theory based on an expansion in the sequence disorder. We
show that there is a continuous phase transition from a molten phase at higher
temperatures to a low-temperature glass phase. The primary freezing occurs
above the critical temperature, with local islands of stable folds forming
within the molten phase. The size of these islands defines the correlation
length of the transition. Our results include critical exponents at the
transition and in the glass phase.Comment: 4 pages, 8 figures. v2: presentation improve
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