Towards a precise lattice determination of the leading hadronic contribution to(g-2)_mu

We report on a recent computation of the leading hadronic contribution to the anomalous magnetic moment of the muon using two dynamical flavours of non-perturbatively O(a) improved Wilson fermions. The strange quark is introduced in the quenched approximation. Partially twisted boundary conditions are applied to improve the momentum resolution in the relevant convolution integral. Our results, obtained at three different values of the lattice spacing allow for a preliminary study of discretization effects. We explore a wide range of lattice volumes, namely 2.2fm