PION-NUCLEON SIGMA-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 a0.14 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 s̄s is fairly large in our result. © 1995 The American Physical Society.