Nonperturbative region of effective strong coupling

TL;DR

This paper investigates the behavior of the strong coupling constant in the nonperturbative region below 1 GeV using a covariant quark model, analyzing meson properties and nucleon spin rules to infer a frozen coupling regime.

Contribution

It provides a novel analysis of the strong coupling constant's behavior in the nonperturbative regime based on meson data and nucleon spin constraints, suggesting a frozen coupling near 0.65-0.72.

Findings

Estimated lpha_s(0) rom 0.65 to 0.72 as a frozen regime

Analysis of meson decay constants and masses consistent with a nonperturbative lpha_s behavior

Discussion of implications for QCD in the low-energy regime

Abstract

In the framework of Poincar\'{e} covariant quark model the behavior of running coupling constant $\alpha_{s}\left(Q^{2}\right)$ is considered in $Q < 1 \mbox{GeV}$ region. An analysis was carried out for pseudoscalar and vector mesons with lepton decay constants, masses (obtained from model dependent) and nucleon spin rules required to match their experimental counterparts. Possible behavior of $\alpha_{s}$ with $\alpha_{\mathrm{crit.}}=\alpha_{s}\left(Q^{2}=0\right) \sim 0.65-0.72$ in the case of a frozen regime, which follows from experimental values of lepton decay constant, masses and nucleon spin rules are discussed.