Simple analytic QCD model with perturbative QCD behavior at high momenta

TL;DR

This paper introduces a simple analytic QCD model that maintains perturbative behavior at high energies while parametrizing low-energy unknowns with a delta function, reducing free parameters and fitting tau decay data.

Contribution

It proposes a new analytic QCD model with a single free parameter, matching perturbative QCD at high energies and incorporating low-energy behavior through a delta function.

Findings

Model reproduces high-energy perturbative QCD behavior.

Single free parameter fixed by tau decay ratio.

Maintains correct analytic properties of the coupling.

Abstract

Analytic QCD models are those where the QCD running coupling has the physically correct analytic behavior, i.e., no Landau singularities in the Euclidean regime. We present a simple analytic QCD model in which the discontinuity function of the running coupling at high momentum scales is the same as in perturbative QCD (just like in the analytic QCD model of Shirkov and Solovtsov), but at low scales it is replaced by a delta function which parametrizes the unknown behavior there. We require that the running coupling agree to a high degree with the perturbative coupling at high energies, which reduces the number of free parameters of the model from four to one. The remaining parameter is fixed by requiring the reproduction of the correct value of the semihadronic tau decay ratio.