The Majorana particles and the Majorana sea
  Can one make a Majorana field theory for fermions starting from the zero mass Weyl theory, then adding a mass term as an interaction? The answer to this question is: yes we can. We can proceed similarly to the case of the Dirac massive field theory. In both cases one can start from the zero mass Weyl theory and then add a mass term as an interacting term of massless particles with a constant (external) field. In both cases the interaction gives rise to a field theory for a free massive fermion field. We present the procedure for the creation of a mass term in the case of the Dirac and the Majorana field and we look for a massive field as a superposition of massless fields. 
N. Mankoc Borstnik (Univ. of Ljubljana, Jozef Stefan Institute), H. B.   Nielsen (Dept. of Physics, Niels Bohr Institute), C...