arXiv subjects

Andrea Pagnani

Publications and source records attributed to Andrea Pagnani.

39 records · Page 3Linked to original sources

arXiv2003

Scalings of domain wall energies in two dimensional Ising spin glasses

We study domain wall energies of two dimensional spin glasses. The scaling of these energies depends on the model's distribution of quenched random couplings, falling into three different classes. The first class is associated with the exponent theta =-0.28, the other two classes have theta = 0, as can be justified theoretically. In contrast to previous claims, we find that theta=0 does not indicate d=d_l but rather d <= d_l, where d_l is the lower critical dimension.

cond-mat.dis-nn↗

arXiv2001

Zero Temperature Properties of RNA Secondary Structures

We analyze different microscopic RNA models at zero temperature. We discuss both the most simple model, that suffers a large degeneracy of the ground state, and models in which the degeneracy has been remove, 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 $θ\simeq 1/3$.

cond-mat.dis-nn↗

arXiv1999

Testing a Variational Approach to Random Directed Polymers

The one dimensional direct polymer in random media model is investigated using a variational approach in the replica space. We demonstrate numerically that the stable point is a maximum and the corresponding statistical properties for the delta correlated potential are in good agreements with the known analytic solution. In the case of power-law correlated potential two regimes are recovered: a Flory scaling dependent on the exponent of the correlations, and a short range regime in analogy with the delta-correlated potential case.

cond-mat.dis-nn↗