A "DUAL" MODEL OF A MASSIVE SPIN-1/2 POINT PARTICLE, AND A THEORETICAL EXPLANATION FOR THE EFFECT OF "MAXIMAL PARITY-VIOLATION"

The open question left by elementary particle physics about the origin of the so-called ``maximal parity-violation'' is dealt with. It is shown that an actual theoretical answer could be found within a new relativistic quantum field formalism being a strictly covariant fermion--antifermion extension of the usual one for massive fermions. This formalism can account naturally for the effect at issue, in such a way as even to restore both parity and charge-conjugation symmetries: it spontaneously provides a true ``chiral field'' approach, which gives rise to the conjecture of a pseudoscalar (extra) charge variety anticommuting with the scalar (ordinary) one and just underlying the ``maximally parity-violating'' phenomenology. A dual - either ``Dirac'' or ``chiral'' - fermion model may be introduced accordingly, which redepicts any massive spin-1/2 point fermion as a particle being able to manifest two mutually exclusive, scalar- and pseudoscalar-charge-eigenstate natures, both singly respecting (though in opposite ways) ordinary mirror symmetry. The zero-mass limit would bring this internal duality to its extreme consequences: what would be automatically left is a pure two-component particle model that universally redefines a massless spin-1/2 fermion and the related antifermion as two strict pseudoscalar-charge eigenstates being just the mirror images of each other and at most carrying scalar (additional) charges bound to a maximal uncertainty in sign. Such an outcome may be expected to lead to a better understanding of the origin itself of fermion masses, since it can now be stated that only by acquiring a mass, and by gaining an extra helicity freedom degree, a fermion may also appear as a regular scalar-charge eigenstate.