An Elementary (Pseudo)Scalar at all scales

TL;DR

This paper explores a modified QCD model where scalar particles are elementary at all energy scales due to an ultraviolet fixed point, challenging the usual confinement paradigm.

Contribution

It introduces an extended linear sigma model with quarks and gluons, demonstrating scalars as elementary particles across all energy scales via a UV fixed point.

Findings

Scalars are elementary at high energies due to asymptotic freedom.

The model exhibits a UV fixed point with all couplings asymptotically free.

Scalars are not confined at low energies, remaining elementary.

Abstract

We consider an extended linear $\sigma $ model in which the fermions are quarks and are coupled to gluons. Equivalently, this is QCD extended by coupling the quarks to a colour singlet chiral multiplet of ($ \sigma, \vec \pi $) fields. This theory has a phase governed by a UV fixed point where all couplings are AF (asymptotically free). This implies that the scalars are elementary at high energies (UV) and, as they are colour singlets, they are not confined at low energy (IR). Thus, the scalar particles are elementary at all scales.