K⁰--bar{K}⁰ mixing in full lattice QCD

There are at least two methods to calculate $ B_K $ with staggered fermions: one is the two spin trace formalism and the other is the one spin trace formalism. We have performed numerical simulations on a $ 16^3 \times 40 $ lattice in full QCD with $ \beta = 5.7 $ and a dynamical quark mass 0.01 in lattice units. We try various sources to select only the pseudo-Goldstone bosons and compare the various results.