Biomedical subjects

Pietro Parruccini

Publications and source records attributed to Pietro Parruccini.

2 recordsLinked to original sources

PubMed2004

Crossover behavior in three-dimensional dilute spin systems.

We study the crossover behaviors that can be observed in the high-temperature phase of three-dimensional dilute spin systems, using a field-theoretical approach. In particular, for randomly dilute Ising systems we consider the Gaussian-to-random and the pure-Ising-to-random crossover, determining the corresponding crossover functions for the magnetic susceptibility and the correlation length. Moreover, for the physically interesting cases of dilute Ising, XY, and Heisenberg systems, we estimate several universal ratios of scaling-correction amplitudes entering the high-temperature Wegner expansion of the magnetic susceptibility, of the correlation length, and of the zero-momentum quartic couplings.

Journal Article↗

PubMed2003

Evaluation of the improvement parameter in the lattice Hamiltonian approach to critical phenomena.

In lattice Hamiltonian systems with a quartic coupling gamma, a critical value gamma(*) may exist such that, when gamma=gamma(*), the leading irrelevant operator decouples from the Hamiltonian and the leading nonscaling contribution to renormalization-group invariant physical quantities (evaluated in the critical region) vanishes. The 1/N expansion technique is applied to the evaluation of gamma(*) for the lattice Hamiltonian of vector spin models with O(N) symmetry. As a byproduct, systematic asymptotic expansions for the relevant lattice massive one-loop integrals are obtained.

Journal Article↗