Unconstraining the Unhiggs

TL;DR

This paper examines the unitarity of the Unhiggs model for heavy quark and gauge boson scattering, exploring its phenomenology at the LHC and proposing a conformally invariant Yukawa coupling to extend unitarity bounds.

Contribution

It introduces a new conformally invariant Yukawa coupling in the Unhiggs model, extending unitarity to higher scaling dimensions using AdS/CFT correspondence.

Findings

Unitarity preserved for d ≤ 1.5 with original Yukawa coupling.

LHC phenomenology can test the Unhiggs model in certain parameter ranges.

New Yukawa coupling ensures unitarity for 1 ≤ d < 2.

Abstract

We investigate whether or not perturbative unitarity is preserved in the Unhiggs model for the scattering process of heavy quarks and longitudinal gauge bosons $\bar q q \to V_L^+ V_L^-$. With the Yukawa coupling given in the original formulation of the Unhiggs model, the model preserves unitarity for Unhiggs scaling dimensions $d\leq 1.5$. We examine the LHC phenomenology that is implied by the Unhiggs model in this parameter range in detail and discuss to what extent the LHC can test $d$ if an excess is measured in the phenomenologically clean $ZZ$ channel in the future or if the LHC measurement remains consistent with the background. We then make use of the AdS/CFT correspondence to derive a new Yukawa coupling that is conformally invariant at high energies, and show that with this Yukawa coupling the theory is unitary for $1 \leq d < 2$.