Quark masses without Yukawa hierarchies
  A model based on the local gauge group SU(3)_c x SU(3)_L x U(1)_X without particles with exotic electric charges is shown to be able to provide the quark mass spectrum and their mixing, by means of universal see-saw mechanisms, avoiding a hierarchy in the Yukawa coupling constants. 
H. Fanchiotti (1), C. Garcia-Canal (1), W. A. Ponce (2). ((1) U.   Nacional de La Plata, Argentina. (2) U. de Antioqua, Colo...