The Higgs as a portal to Plasmon-like unparticle excitations

A renormalizable coupling between the Higgs and a scalar unparticle operator U of non-integer dimension d U<2 triggers, after electroweak symmetry breaking, an infrared divergent vacuum expectation value for U. Such IR divergence should be tamed before any phenomenological implications of the Higgs-unparticle interplay can be drawn. In this paper we present a novel mechanism to cure that IR divergence through (scale-invariant) unparticle self-interactions, which has properties qualitatively different from the mechanism considered previously. Besides finding a mass gap in the unparticle continuum we also find an unparticle pole reminiscent of a plasmon resonance. Such unparticle features could be explored experimentally through their mixing with the Higgs boson.