Pion-nucleon σ term in lattice QCD

We calculate both the connected and disconnected contributions to the {π}-N {σ} term in quenched lattice QCD with the Wilson quark action on a 12³×{}20 lattice at {β}=5.7 with the lattice spacing a{}0.14 fm. The latter is evaluated with the variant wall source method, previously applied successfully for {π}-{π} scattering lengths and the {η}' meson mass. We found the disconnected contribution to be about twice as large as the connected one. The value for the full {π}-N {σ} term {σ}=40--60 MeV is consistent with the experimental estimates. The nucleon matrix element of the strange quark density s{}s is fairly large in our result.