Evading the Few TeV Perturbative Limit in 3-3-1 Models
  Some versions of the electroweak SU(3)$_L\otimesU(1)_X$ models cannot be treated within perturbation theory at energies of few TeV. An extended version for these models is proposed which is perturbative even at TeV scale posing no threatening inconsistency for test at future colliders. The extension presented here needs the addition of three octets of vector leptons, which leave three new leptonic isotriplets in the SU(2)$_L\otimesU(1)_Y$ subgroup. With this representation content the running of the electroweak mixing angle, $\theta_W (\mu)$, is such that $\sin^2\theta_W(\mu)$ decreases with the increase of the energy scale $\mu$, when only the light states of the Standard Model group are considered. The neutral exotic gauge boson $Z^\prime$ marks then a new symmetry frontier. 
Alex G. Dias