Non-Perturbative Renormalisation of the Lattice Δs=2 Four-Fermion Operator

Original · EN

We compute the renormalised four-fermion operator OΔˢ⁼² using a non-perturbative method recently introduced for determining the renormalisation constants of generic lattice composite operators. Because of the presence of the Wilson term, OΔˢ⁼² mixes with operators of different chiralities. A projection method to determine the mixing coefficients is implemented. The numerical results for the renormalisation constants have been obtained from a simulation performed using the SW-Clover quark action, on a 16³ × 32 lattice, at β=6.0. We show that the use of the constants determined non-perturbatively improves the chiral behaviour of the lattice kaon matrix element K⁰| OΔˢ⁼² | K⁰.