2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/192066We report on our recent study of flavor singlet matrix elements calculated with the wall source method without gauge fixing. Results are presented for the mass difference between $η^{\prime}$ and pseudoscalar octet mesons, the $π$-N $σ$ term and the proton axial vector matrix elements. An exploratory calculation of the N-N scattering lengths is also discussed including a phenomenological study with one-boson exchange potentials.12 pages, latex source-file, 5 figures as epsf-file, talk presented at ''QCD on massively parallel computers'' (Yamagata, Japan, March 16-18 1995)High Energy Physics - Latticetext