Radiative corrections to the magnetic moments of the proton and the neutron

We estimate the radiative corrections of order alpha/pi to the magnetic moments of the proton and the neutron. The photon-loop diagram of the vertexcorrection type is evaluated with phenomenological nucleon vector form factors. Infrared-finiteness and gauge-invariance require the inclusion of the wave-function renormalization factor from the self-energy diagram. Using recent empirical form factor parametrizations, the corrections amount to delta(kappa p) = -3.42 x 10(-3) and delta(kappa n)= 1.34 x 10(-3). We also study the effects from photon loops with internal Delta(1232) isobars. For two customary versions of the Delta N gamma vertex and spin-3/2 propagator, these radiative corrections have values of delta((Delta))(kappa p) =(-0.9, 0.0) x 10(-3) and delta((Delta))(kappa n) = (1.2,-0.8) x 10(-3), respectively. Taking these ranges as a systematic error, our estimates read delta(kappa p) = (-3.9 +/- 0.4) x 10(-3) and delta(kappa n) = (1.5 +/- 1.0) x 10(-3).