Restoring chiral symmetry to O(a^2) for dynamical Wilson fermions
  We present results for the non-perturbative determination of the improvement and renormalization factors of the isovector axial current for lattice QCD with two flavors of dynamical Wilson quarks. The improvement and normalization conditions are formulated in terms of matrix elements of the PCAC relation in the Schroedinger functional setup and results are given in the form of interpolating formulae for bare gauge couplings beta=6/g_0^2>5.2. 
Roland Hoffmann, Michele Della Morte, Francesco Knechtli, Rainer   Sommer, Ulli Wolff