Spectroscopy of SU(4) composite Higgs theory with two distinct fermion representations

TL;DR

This study simulates an SU(4) gauge theory with two fermion types to explore its meson spectrum, providing insights relevant for composite Higgs models with partially composite top quarks.

Contribution

It presents the first lattice simulation of SU(4) with fundamental and sextet fermions, analyzing the meson spectrum and chiral properties in this context.

Findings

Meson spectrum consistent with large-Nc scaling

Pseudoscalar masses and decay constants fit chiral perturbation theory

Goldstone boson properties inferred from the model

Abstract

We have simulated the SU(4) lattice gauge theory coupled to dynamical fermions in the fundamental and two-index antisymmetric (sextet) representations simultaneously. Such theories arise naturally in the context of composite Higgs models that include a partially composite top quark. We describe the low-lying meson spectrum of the theory and fit the pseudoscalar masses and decay constants to chiral perturbation theory. We infer as well the mass and decay constant of the Goldstone boson corresponding to the non-anomalous U(1) symmetry of the model. Our results are broadly consistent with large-Nc scaling and vector-meson dominance.