The Higgs as a Portal to Plasmon-like Unparticle Excitations

TL;DR

This paper proposes a new mechanism involving unparticle self-interactions to resolve infrared divergences caused by Higgs-unparticle couplings, revealing potential experimental signatures like a plasmon-like resonance.

Contribution

It introduces a novel scale-invariant unparticle self-interaction mechanism that cures IR divergence and predicts a plasmon-like resonance in the unparticle spectrum.

Findings

A mass gap in the unparticle continuum was identified.

An unparticle pole resembling a plasmon resonance was discovered.

Potential experimental signatures through Higgs-unparticle mixing were suggested.

Abstract

A renormalizable coupling between the Higgs and a scalar unparticle operator O_U of non-integer dimension d_U<2 triggers, after electroweak symmetry breaking, an infrared divergent vacuum expectation value for O_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.