PI-N-SIGMA TERM AND QUARK SPIN CONTENT OF THE NUCLEON

We report results of our calculation on the pi N sigma term and quark spin content of the nucleon on the quenched 16(3) x 24 lattice at beta = 6.0. The disconnected insertions which involve contributions from the sea quarks are calculated with the stochastic Z(2) noise algorithm. As a physical test of the algorithm, we show that the forward matrix elements of the vector and pseudoscalar currents for the disconnected insertions are indeed consistent with the known results of zero. We tried the Wuppertal smeared source and found it to be more noisy than the point source. With unrenormalized m(q) = 4.42(17)MeV, we find the pi N sigma term to be 39.2 +/- 5.2 MeV. The strange quark condensate in the nucleon is large, i.e. (N\($) over bar ss\N) = 1.16 +/- 0.54. For the quark spin content, we find Delta u = 0.78 +/- 0.07, Delta d = -0.42 +/- 0.07, and Delta s = -0.13 +/- 0.06. The flavor-singlet axial charge g(A)(1) = Delta Sigma = 0.22 +/- 0.09.