Dirac, Majorana and Weyl fermions

Abstract

This is a pedagogical article which discusses various kinds of fermion fields: Dirac, Majorana and Weyl. The definitions and motivations for introducing each kind of fields is discussed, along with the connections between them. It is pointed out that these definitions have to do with the proper Lorentz group, and not with respect to any discrete symmetry. The relationship of discrete symmetries like charge conjugation and CP, particularly important for Majorana fermions, has also been clarified.

Comments: 32 pages, LaTeX, no figure. A new section added on the 2-component formalism, and the section on "Feynman rules" has been expanded. The changes in the other section are minor