We construct a class of theories which are scale-invariant on quantum level in all orders of perturbation theory. In a subclass of these models scale invariance is spontaneously broken, leading to the existence of a massless dilaton. All mass scales in this type of theories come from one and the same source. The applications of these results to the problem of stability of the electroweak scale against quantum corrections, to the cosmological constant problem, to dark energy and inflation are discussed.

EPFL Lausanne