Logarithmic corrections to O(a2) lattice artifacts

We compute logarithmic corrections to the O(a(2)) lattice artifacts for a class of lattice actions for the non-linear O(n) sigma-model in two dimensions. The generic leading artifacts are of the form a(2)vertical bar In(a(2))vertical bar(n/(n-2)). We also compute the next-to-leading corrections and show that for the case n = 3 the resulting expressions describe well the lattice artifacts in the step scaling function, which are in a large range of the cutoff apparently of the form O(a). An analogous computation should, if technically possible, accompany ally precision measurements in lattice QCD. (C) 2009 Elsevier B.V. All rights reserved.