The four-fermion operators of the weak hamiltonian on the lattice and in the continuum

The relation between four-fermion operators on the lattice and the corresponding operators in the continuum is computed at first order in perturbation theory. A first evaluation of the matrix elements of these operators, which are essential for theoretical predictions for weak non-leptonic decays such as the ΔT=1/2 and the ΔT=3/2 rates for K meson decays, has been recently performed using Monte Carlo techniques. (orig.)