We report on a lattice QCD calculation of the πN σ term, the scalar form factor, and N |ss|N . The disconnected insertion part of σ πN is found to be 1.8 ± 0.1 times larger than the connected insertion contribution. The q 2 dependence of σ πN (q 2 ) is about the same as G E (q 2 ) of the proton so that σ πN (2m 2 π )−σ πN (0) = 6.6±0.6 MeV. The ratio y = N |ss|N / N |ūu+dd|N = 0.36 ± 0.03. Both results favor a σ πN ∼ 53 MeV, slightly larger than our direct calculation of σ πN = 49.7 ± 2.6 MeV. We also compute F s and D s and find that the agreement with those from the octect baryon mass splittings crucially depends on the inclusion of the large disconnected insertion. Finally, we give our result for the KN σ term.

We compute the ma dependence of lattice renormalization factors for sea quark matrix elements. The results differ from the (1 + ma) correction factor commonly used for valence quarks and connected current insertions. We find that for sea quarks, the correction factors are in general larger and depend strongly on the Lorentz structure of the current under consideration. Results are presented both for the Wilson action and for the 2-link improved action of Hamber and Wu. Phenomenological implications are also briefly discussed in two examples.