Lattice Evaluation of Strong Corrections to Weak Matrix Elements - the Delta-I Equals One-Half Rule.

A lattice Monte Carlo technique for the evaluation of the transition elements of nonleptonic decays is described. Emphasis is placed on the investigation of the origin of the (DELTA)I = 1/2 rule. An operator product expansion and chiral perturbation theory provide the analytical basis of the calculation. A new class of previously incomputable graphs is seen to be of much greater numerical importance than another, more easily calculated, set. The exponentiation of a meson field proves crucial in enabling lattice Green functions to be computed by standard matrix inversion procedures. Simpler Green functions, examined as a test of numerical techniques, produce measurements of hadronic and magnetic moments. The use of free boundary conditions in the lattice's temporal direction allows for a clean separation of the lowest lying hadrons from their excitations.