Neutrino mass as a consequence of the exact solution of 3-3-1 gauge   models without exotic electric charges
  The unjustly neglected method of exactly solving generalized electro-weak models - with an original spontaneous symmetry breaking mechanism based on the gauge group $SU(n)_{L}\otimes U(1)_{Y}$ - is applied here to a particular class of chiral 3-3-1 models. This procedure enables us - without resorting to any approximation - to express the boson mass spectrum and charges of the particles involved therein as a straightforward consequence of both a proper parametrization of the Higgs sector and a new generalized Weinberg transformation. We prove that the resulting values can be accommodated to the experimental ones just by tuning a sole parameter. Furthermore, if we take into consideration both the left-handed and right-handed components of the neutrino (included in a lepton triplet along with their corresponding left-handed charged partner) then we are in the position to propose an original method for the neutrino to acquire a very small but non-zero mass without spoiling the previously achieved results in the exact solution of the model. In order to be compatible with the existing phenomenological data, the range of that sole parameter imposes in our method a large order of magnitude for the VEV $<\phi>\sim10^{6}$ TeV. Consequently, the new bosons of the model have to be very massive.   PACS numbers: 14.60.St; 12.60.Cn; 12.60.Fr 
Adrian Palcu