Federico Ricci-Tersenghi

PubMed2002

Dynamic phase transition for decoding algorithms.

The state-of-the-art error correcting codes are based on large random constructions (random graphs, random permutations, etc.) and are decoded by linear-time iterative algorithms. Because of these features, they are remarkable examples of diluted mean-field spin glasses, both from the static and dynamic points of view. We analyze the behavior of decoding algorithms by mapping them onto statistical-physics models. This allows us to understand the intrinsic (i.e., algorithm independent) features of this behavior.

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PubMed2002

Zero-temperature properties of RNA secondary structures.

We analyze different microscopic RNA models at zero temperature. We discuss both the most simple model, which suffers a large degeneracy of the ground state, and models in which the degeneracy has been removed in a more or less severe manner. We calculate low-energy density of states using a coupling perturbing method, where the ground state of a modified Hamiltonian, that repels the original ground state, is determined. We evaluate scaling exponents starting from measurements of overlaps and energy differences. In the case of models without accidental degeneracy of the ground state we are able to clearly establish the existence of a glassy phase with theta approximately 1/3. 87.15.Aa, 64.60.Fr

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