Z DEPENDENCE OF RADIATIVE CORRECTIONS TO BETA DECAY

We show that to first order in α, and with neglect of effects which vanish in the limit of zero lepton momenta, the theoretical ft value in 0 → 0 Fermi transitions is independent of Z. The only model-dependent feature of this argument is in the treatment of effects induced by the axial current. It is further shown that in higher order radiative corrections the power of Z cannot exceed the power of α; the leading term in the radiative correction to the ft value is therefore of order Z2α2. © 1969 The American Physical Society.