Following the same steps as in the Appendix B,
we can construct diagrammatic series for
five order matrix element
.
We have to combine all third and fourth order vertexes
in such a way that we have 2 "incoming" arguments and 3 "out-coming" arguments.
The result of course will be the same if we would consider
3 "incoming" arguments and 2 "out-coming" arguments.
Considering all possible topologies consistent with definitions of
vertexes and Green functions and without internal loops,
we conclude, that there exist 60 diagrams constructed from three third order
verticesand 2 Green functions and 20 diagrams constructed from
one three order vertex, one four order vertex and one Green function.
We call these two groups "3+3+3" and "4+3" correspondingly.
Below are the diagrams and analytical expressions for "3+3+3" and "4+3" terms.
Together with the bare fifth order vertex
this sum gives the full fifth-order
interaction matrix element
or
.
We used these expressions as an input to Matematica, therefore
notation here is slightly different.
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|
|