  The $\alpha^4$ contribution to the lepton $g-2$ from a gauge-invariant set of
18 Feynman diagrams containing a light-by-light scattering subdiagram
internally has been reevaluated by a method independent of the previous
approach. Comparison of two methods revealed a program error in the first
version. Correcting this error, the contributions of these 18 diagrams become
-0.990 72 (10)$(\alpha/\pi)^4$ and -4.432 43 (58)$(\alpha/\pi)^4$ for the
electron and muon $g-2$, respectively. The correction is not large enough to
affect the comparison between theory and experiment for the muon $g-2$, but it
does alter the inferred value for the fine structure constant $\alpha^{-1}$ by
6 ppb.

High Energy Physics - Phenomenology