Parity Doubling and the S Parameter Below the Conformal Window

TL;DR

This study uses lattice simulations to analyze how the spectrum and electroweak S parameter of an SU(3) gauge theory evolve with increasing fermion flavors, revealing parity doubling and a decreasing S parameter.

Contribution

It provides the first lattice results on the spectrum and S parameter for SU(3) theories with 2 and 6 fermions, highlighting trends relevant to conformal transition.

Findings

Spectrum shows increased parity doubling with more fermions.

The S parameter per doublet decreases as N_f increases.

Results suggest potential for reduced electroweak constraints in theories with more fermions.

Abstract

We describe a lattice simulation of the masses and decay constants of the lowest-lying vector and axial resonances, and the electroweak S parameter, in an SU(3) gauge theory with $N_f = 2$ and 6 fermions in the fundamental representation. The spectrum becomes more parity doubled and the S parameter per electroweak doublet decreases when $N_f$ is increased from 2 to 6, motivating study of these trends as $N_f$ is increased further, toward the critical value for transition from confinement to infrared conformality.