  The $SU(3)_c\otimes SU(3)_L\otimes U(1)_N$ model of Pisano and Pleitez
extends the Standard Model in a particularly nice way, so that for example the
anomalies cancel only when the number of generations is divisible by three. The
original version of the model has some problems accounting for the lepton
masses. We resolve this problem by modifying the details of the symmetry
breaking sector in the model.

High Energy Physics - Phenomenology