Parity violations in hydrogen and the fundamental structure of the weak current

Experiments in progress with hydrogen and deuterium may in practice determine the fundamental parameters and constituents of the weak interaction within the framework of unified gauge theories. In particular, for SU (2) × U (1) theories, from the results of these experiments one can infer the masses of the charged and neutral weak vector bosons (and thus sin²θ_W), and the isospin classification of the right-handed portions of the electron and the u- and d-quarks. Non-singlet assignments for e_R, u_R and d_R would imply the existence of additional leptons and/or quarks. Hydrogen/deuterium data also may be used to discriminate between SU (2) × U (1) models and various models based on larger gauge groups.