  We study a scale invariant two measures theory where a dilaton field \phi has
no explicit potentials. The scale transformations include a shift
\phi\to\phi+const. The theory demonstrates a new mechanism for generation of
the exponential potential: in the conformal Einstein frame (CEF), after SSB of
scale invariance, the theory develops the exponential potential and, in
general, non-linear kinetic term is generated as well. The possibility of
quintessence and of halo dark matter solutions are shown. The regime where the
fermionic matter dominates (as compared to the dilatonic contribution) is
analyzed. There it is found that starting from a single fermionic field we
obtain exactly three different types of spin 1/2 particles in CEF that appears
to suggest a new approach to the family problem of particle physics. It is
automatically achieved that for two of them, fermion masses are constants,
gravitational equations are canonical and the "fifth force" is absent. For the
third type of particles, four fermionic interaction appears from SSB of scale
invariance.
