Sources of FCNC in $SU(3)_C \otimes SU(3)_L \otimes U(1)_X$ models
  There are different models based on the gauge symmetry $SU(3)_C \otimes SU(3)_L \otimes U(1)_X$ (331) some of them includes exotic particles and others are constructed without any exotic charges assigned to the fermionic spectrum. Each model build up on 331 symmetry has its own interesting properties according to the representations of the gauge group used for the fermionic spectrum; that is the main reason to explore and identify the possible sources of flavor changing neutral currents and lepton flavor violation at tree level. 
J. M. Cabarcas, J. Duarte and J-Alexis Rodriguez
hep-ph