We utilize precise weak interaction experiments on atomic muon capture and beta decay in the A = 3 nuclei, and take into account the effects of nuclear anomalous thresholds to extract the pseudoscalar pi-^3He-^3H coupling parameter, G^{eff}(m_pi^2) = 45.8+- 2.4. This is an order of magnitude improvement in precision over that from the use of pion-nuclear scattering data and dispersion relations.
Download