FIVE-LOOP -EXPANSIONS FOR RANDOM ISING MODEL AND MARGINAL SPIN DIMENSIONALITY FOR CUBIC SYSTEMS

Abstract The ϵ for critical exponents of the weakly disordered Ising model are calculated up to the five-loop order and found to possess coefficients with irregular signs and values. The estimate nc = 2.855 for the marginal spin dimensionality of the cubic model is obtained by the Pade-Borel resummation of the corresponding five-loop ϵ-expansion.