Phantom Higgs from Unparticles

TL;DR

This paper explores how coupling the Higgs to unparticles can create a new, lighter Higgs-like state with reduced couplings, potentially altering collider search expectations.

Contribution

It introduces the concept of a phantom Higgs arising from Higgs-unparticle interactions, showing how it can appear below the mass gap with suppressed couplings.

Findings

A mass gap is generated in the unparticle continuum after electroweak symmetry breaking.

A new isolated state, the phantom Higgs, can appear near or below the mass gap.

The phantom Higgs has universally reduced couplings to fermions and gauge bosons.

Abstract

A renormalizable coupling between the Higgs and a scalar unparticle operator O_U of non-integer dimension d_U < 2 gives rise, after electroweak symmetry breaking, to a mass gap in the unparticle continuum and a shift in the original Higgs mass, which can end up above or below the mass gap. We show that, besides the displaced Higgs state, a new isolated state can generically appear in the spectrum near or below the mass gap. Such state (which we call phantom Higgs) is a mixture of Higgs and unparticles and therefore has universally reduced couplings to fermions and gauge bosons. This phenomenon could cause the mass of the lightest Higgs state accessible to colliders to be much smaller than the mass expected from the SM Lagrangian.