Journal of Physical Studies
A marginal dimension of a weakly diluted quenched m-vector model
Yurij V. Holovatch, M. Dudka, Taras Yavors’kii
Abstract
We calculate a marginal order parameter dimension mc which in a weakly diluted quenched mvector model controls the crossover from a universality class of a \pure" model (m > mc) to a new universality class (m < mc).Exploiting the Harris criterion and the eld-theoretical renormalization group approach allows us to obtain mc as a ve-loop "-expansion as well as a six-loop pseudo-" expansion.In order to estimate the numerical value of mc we process the series by precisely adjusted Pad e{Borel{Leroy resummation procedures.Our nal result mc = 1:912 0:004 < 2 stems from the longer and more reliable pseudo-" expansion, suggesting that a weak quenched disorder does not change the values of xy-model critical exponents as it follows from the experiments on critical properties of He 4 in porous media.