Chiral Symmetry of Neutrino

In this paper (i) is given a new representation for gamma matrices in which is confirmed theoretically the absence of positive helicity neutrino and respectively negative helicity antineutrino, (ii) is proved the equivalence of Dirac equation for mass m with Proca equation for mass 2m, and (iii) is proposed a discrete symmetry group for weak and strong interactions built with 4 unitary and 4 nilpotent operators. The cosmological constant predicted by theory is Λ = 2πG(c/ℏ)^3m^4, where m is neutrino mass.