Vertex corrections in infrared absorption in superconducting and normal metals

Abstract

Abstract We have calculated the frequency dependent electromagnetic absorption in both the superconducting and normal states for a model of a strong-coupling superconductor. We have done this in the absence of vertex corrections and also with the inclusion of vertex corrections in a certain approximation. We find that in the range of phonon energies the vertex correction is quite small for the normal state. The same is true for the superconducting state except near the gap. This correction tends to bring the theory into closer agreement with experiments on the absorption in Pb.