B_K from quenched overlap QCD
  We present an exploratory calculation of the standard model Delta S=2 matrix element relevant for indirect CP violation in K -> pi pi decays. The computation is performed with overlap fermions in the quenched approximation at beta=6.0 on a 16^3x32 lattice. The resulting bare matrix element is renormalized non-perturbatively. Our preliminary result is B_K^{NDR}(2 GeV)=0.61(7), where the error does not yet include an estimate of systematic uncertainties. 
N. Garron (1), L. Giusti (1,2), C. Hoelbling (1), L. Lellouch (1), C.   Rebbi (3) ((1) CPT Marseille, (2) CERN, (3) Boston U...