Dirac and Majorana Feynman Rules with four-fermions

Understand

A compact method for amplitude calculations in theories with Dirac and Majorana effective operators is discussed.

• Using the renormalizable formalism of Denner et al., [1,2] for propagators, vertices and fermion (number) flow and introducing new "reading-rules", it is shown that fermions can be treated as scalars in the diagrams.
• The effect of Fermi-statistics appears only in overall signs and is determined once for whole classes of diagrams.
• Each vertex in this method corresponds to two or more vertices in the standard treatment of effective theories.