Origin of mass scales and hierarchies

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As the operation of the LHC looms near, the number of new physics models being seriously considered has never been greater. New physics is needed to complete our picture of the unification of the two of the four forces of nature as described by the decades old standard model of electroweak interactions. The symmetry breaking inherent in this description requires the appearance of a new mass scale, but there has been no confirmed understanding of the origin of this mass scale. At about three orders of magnitude lower in energy than the electroweak scale is the mass scale of QCD, describing a third fundamental force of nature. With QCD nature provides an example of how a mass scale can have a dynamical origin in a strongly interacting gauge theory. Surpisingly, most proposals for the origin of the electroweak mass scale differ significantly from the QCD example. The popular proposals involve concepts that have not yet been seen in nature (elementary scalar fields, superpartners, extra dimensions, string theories, etc.). My research pursues a more conservative approach, more in line with clues provided by QCD. I will continue to elaborate on the signals that this may imply for LHC physics and I will continue to study the related implications for the remaining questions of mass and flavor. An intriguing possibility is the idea that strong gauge interactions also underly gravitation, the fourth force of nature. This is through the phenomenon of "induced gravity", and it requires a better understanding of vacuum energy in theories like massless QCD. Contributing to this understanding are recent results from experiment, lattice studies, and other nonperturbative approaches to low energy QCD.