Superallowed nuclear β decay as a probe of the standard model

Precise measurements of the β decay between nuclear states provide a demanding test both of CVC and of the Standard Model. Each measured transition is characterized by an Jt value, which depends on three experimental quantities - the half life, branching ratio and decay energy - and on theoretical calculations that include radiative and charge corrections. Substantial advances have been made recently on all fronts, with the result that eight Jt values are now known to a precision of ± 0.15% or better. The data are outlined, with special emphasis on the most recent techniques; the consistency of the results are also displayed and the significance of the calculated corrections described. The global data are then analyzed for their impact on CVC and to determine the Vud element of the Kobayashi-Maskawa matrix, thus testing the adequacy of the three-generation Standard Model. Finally, the results are used to extract the Fierz constant, set a limit on heavy-neutrino mixing and establish consistency with pion, neutron and non-O+ superallowed nuclear β decay