Weyl fermions are massless
Majorana fermions are real
Dirac fermions make sense.
The first two have two degrees of freedom; the latter has four.
WHY do Weyl fermions have four degrees of freedom once they go off-shell?
I’m counting: (spin up / spin down) x (particle / antiparticle) = 4.
But then I’m afraid I have to go back to asking why this counting doesn’t hold on the mass shell also. Weyls fermions are distinguishable from their antiparticles since they are complex, and they have spin 1/2, which can point up/down. Is there some restriction on the relationship between spin/particle type that vanishes off shell?