Physical Naturalness and Dynamical Breaking of Classical Scale Invariance

The recent LHC data may suggest that the paradigm of naturalness, which has overwhelmingly guided model building beyond the standard model, should be revised. In a scheme-independent view of regularisation only physical mass scales give contributions of the order of that scale to the renormalised Higgs mass parameter. A self-consistent picture of electroweak symmetry breaking and renormalisation then emerges if, at the classical level, the space-time symmetry of the fundamental Lagrangian is maximally enhanced to the conformal group, which is ultimately broken down to the Lorentz group by quantum effects. That is, the Lagrangian is taken to be classically scale invariant, implying that any explicit mass scales are absent. As a concrete mechanism for generating the electroweak scale and providing dark matter candidates, we propose a model of a confining dark sector, dark technicolor, that communicates with the standard model only through the Higgs portal.