Composite Higgs model at a conformal fixed point

TL;DR

This paper constructs a composite Higgs model using a conformal fixed point, demonstrating hyperscaling and predicting TeV-scale hadronic states, with a unique light scalar behavior.

Contribution

It introduces a novel approach to building a chirally broken model at a conformal fixed point by manipulating flavor masses, verified through lattice simulations.

Findings

Hadronic states in the 2-3 TeV range

Scalar state nearly degenerate with pion

Scalar mass less than half of vector resonance mass

Abstract

We propose to construct a chirally broken model based on the infrared fixed point of a conformal system by raising the mass of some flavors while keeping the others massless. In the infrared limit the massive fermions decouple and the massless fermions break chiral symmetry. The running coupling of this system "walks" and the energy range of walking can be tuned by the mass of the heavy flavors. Renormalization group considerations predict that the spectrum of such a system shows hyperscaling. We have studied a model with four light and eight heavy flavors coupled to SU(3) gauge fields and verified the above expectations. We determined the mass of several hadronic states and found that some of them are in the 2-3 TeV range if the scale is set by the pseudoscalar decay constant $F_\pi \approx 250$ GeV. The $0^{++}$ scalar state behaves very differently from the other hadronic states. In most of our simulations it is nearly degenerate with the pion and we estimate its mass to be less than half of the vector resonance mass.