Non-perturbative scaling tests of twisted mass QCD

We present a scaling study of lattice QCD with O(a) improved Wilson fermion s and a chirally twisted mass term, in order to get precise results with a moderate computational effort, we have considered a system of physical size of 0.75(3) x 1.5 fm(4) with Schrodinger functional boundary conditions in the quenched approximation. Looking at meson observables in the pseudoscala r and vector channels, we find that O(a) improvement is effective and resid ual cutoff effects are fairly small.