2 research outputs found
Universality classes of three-dimensional -vector model
We study the conditions under which the critical behavior of the
three-dimensional -vector model does not belong to the spherically
symmetrical universality class. In the calculations we rely on the
field-theoretical renormalization group approach in different regularization
schemes adjusted by resummation and extended analysis of the series for
renormalization-group functions which are known for the model in high orders of
perturbation theory. The phase diagram of the three-dimensional -vector
model is built marking out domains in the -plane where the model belongs to
a given universality class.Comment: 9 pages, 1 figur
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