arXiv subjects

Marco Picco

Publications and source records attributed to Marco Picco.

76 records · Page 5Linked to original sources

arXiv1995

RENORMALIZATION GROUP SOLUTION FOR THE TWO-DIMENSIONAL RANDOM BOND POTTS MODEL WITH BROKEN REPLICA SYMMETRY

We find a new solution of the renormalization group for the Potts model with ferromagnetic random valued coupling constants. The solution exhibits universality and broken replica symmetry. It is argued that the model reaches this universality class if the replica symmetry is broken initially. Otherwise the model stays with the replica symmetric renormalization group flow and reaches the fixed point which has been considered before.

hep-th↗

arXiv1995

Renormalisation group calculation of correlation functions for the 2D random bond Ising and Potts models

We find the cross-over behavior for the spin-spin correlation function for the 2D Ising and 3-states Potts model with random bonds at the critical point. The procedure employed is the renormalisation approach of the perturbation series around the conformal field theories representing the pure models. We obtain a crossover in the amplitude for the correlation function for the Ising model which doesn't change the critical exponent, and a shift in the critical exponent produced by randomness in the case of the Potts model. A comparison with numerical data is discussed briefly.

hep-th↗

arXiv1994

Spin--spin critical point correlation functions for the 2D random bond Ising and Potts models

We compute the combined two and three loop order correction to the spin-spin correlation functions for the 2D Ising and q-states Potts model with random bonds at the critical point. The procedure employed is the renormalisation group approach for the perturbation series around the conformal field theories representing the pure models. We obtain corrections for the correlations functions which produce crossover in the amplitude but don't change the critical exponent in the case of the Ising model and which produce a shift in the critical exponent, due to randomness, in the case of the Potts model. Comparison with numerical data is discussed briefly.

hep-th↗

arXiv1994

Numerical study of the Ising spin glass in a magnetic field

We study the order parameter distribution P(q) in the 4d Ising spin glass with $\pm J$ couplings in a magnetic field. We also compare these results with simulations for the infinite ranged model (i.e. SK model.) Then we analyse our numerical results in the framework of the droplet picture as well as in the mean field approach.

cond-mat↗