Homework Statement
I'm supposed to show that the Lindhard dielectric functions gives a contribution to the effective potential of a metals as
U_{eff}( \vec{r} ) \propto \frac{cos( 2 k_{F}r)}{r^{3}}
in the limit of r\rightarrow\infty for d = 3 (3 dimensions)
Homework Equations...
That's a relief.
At least I don't have to "reinvent" Faynmans rules.
But I'm still confused as to which channel/channels the diagrams will be.
For actual particles, one gets clues as to which it might be but how does one figure it out for a field \phi
These where my thoughts at the beginning. I later found a reference in a book by F. Gross, but he's including the charged \Phi K-G fields as well.
In the book, he tells that the first order pertubation (for 2 point) describes the decay the fields. Second order would then describe scattering (2...
I'm reading a course in Introduction to QFT and I'm stuck at a problem.
I'm hoping someone here could point me in the right direction or say if my assumptions are incorrect.
Homework Statement
Derive the Feynman rules and all diagrams at tree-level for \lambda \phi^3 theory using Wick's...