A Theoretical Approach to Pseudogap and Superconducting Transitions in Hole-Doped Cuprates

Figure 6

A few diagrams contributing to the self-energy. The jagged lines carry momentum but no energy. The total momentum entering each impurity vertex, depicted by a dark circle, is zero. We have assumed that impurities are alike, and distributed randomly. Whereas the first two figures correspond to one impurity vertex, the remaining two correspond to the product of four impurity potentials with nonzero averages. These are the cases where two impurities each give rise to two potentials. Thus, the remaining two figures involve the interference of the scattering by more than one impurity. We have assumed low concentration of impurities, and therefore the figures yield smaller contributions compared to those corresponding to the first two and the other diagrams of the same class involving only one impurity vertex.