The analytic result for the radiative correction of order ${\mathrm{\alpha }}^2$(Zα${)}^5$m to the Lamb shift connected with a polarization insertion in one of the two external Coulomb lines is obtained. This correction arises from a gauge-invariant set of diagrams which contain, besides the polarization insertion in the Coulomb leg, all one-loop radiative photon insertions in the electron line with two external Coulomb lines.

• Received 22 October 1996

DOI:https://doi.org/10.1103/PhysRevA.55.2447