We determine quark mass dependent order a improvement terms of the form bJam for non-singlet scalar,
pseudoscalar, vector and axialvector currents, using correlators in coordinate space. We use a set of CLS ensembles
comprising non-perturbatively improved Wilson Fermions and the tree-level Luescher-Weisz gauge action
at β=3.4,3.46,3.55 and β=3.7, corresponding to lattice spacings a ranging from 0.05 fm to 0.09 fm.
We report the values of the bJ improvement coefficients which are proportional to non-singlet quark
mass combinations and also discuss the possibility of determining the ˉbJ coefficients which are proportional
to the trace of the quark mass matrix.
