Multi-representation dynamics of SU(4) composite Higgs models: chiral limit and spectral reconstructions

Abstract

We present a lattice study of the SU(4) gauge theory with two Dirac fermions in the fundamental and two in the two-index antisymmetric representation, a model close to a theory of partial compositeness proposed by G. Ferretti. Focus of this work are the methodologies behind the computation of the spectrum and the extrapolation of the chiral point for a theory with matter in multiple representations. While being still technical, this study provides important steps towards a non-perturbative understanding of the spectrum of theories of partial compositeness, which present a richer dynamics compared to single-representation theories. The multi-representation features are studied first in perturbation theory, and then non-perturbatively by adopting a dual outlook on lattice data through a joint analysis of time-momentum correlation functions and smeared spectral densities.

Strongly coupled gauge theories towards physics beyond the Standard Model

“…The same model has also been studied on the lattice with a focus on the technical developments which might play a crucial role in a non-perturbative understanding of the spectrum of the multirepresentation theories [68,69]. In particular, the possible excited states of a pseudoscalar meson Π in the antisymmetric sector start with ΠΠ, due to the triviality of 𝐺-parity, while in the fundamental sector they start with 𝜋𝜋𝜋 in analogy with QCD.…”

Phase Transitions in Particle Physics

“…The [421,422,423,424,425,426,427] or the adjoint representation [428], and for the SU(4) theory with fermions in the two-index symmetric (decuplet) representation [428,429,430] or with fermions in two distinct representations [431,432,433,434,435,436].…”

Three relativistic neutrons in a finite volume

“…[76]), and the HAL-QCD method [15]. Still another approach, which does not take advantage of finite-volume effects, is to determine multi-hadron observables via smeared spectral functions, extracted from a regulated estimate of the notoriously ill-posed inverse Laplace transform [77][78][79][80][81][82].…”