  If scale invariance is a classical symmetry then both the Planck scale and
the weak scale should emerge as quantum effects. We show that this can be
realized in simple scale invariant theories with a hidden sector. The
weak/Planck scale hierarchy emerges in the (technically natural) limit where
the hidden sector decouples from the ordinary sector. The weak scale is
protected from quadratic divergences because of classical scale invariance, so
there is no hierarchy problem.

High Energy Physics - Phenomenology;High Energy Physics - Theory