The QCD renormalization scale stability of high twists and $\alpha_s$ in deep inelastic scattering

TL;DR

This paper investigates how the choice of QCD renormalization scale affects the extraction of high-twist contributions and the strong coupling constant in deep inelastic scattering, revealing scale-dependent retuning and stability patterns.

Contribution

It provides a detailed analysis of the renormalization scale dependence of high-twist terms and alpha_s in NLO QCD fits to DIS data, highlighting conditions for stability and retuning.

Findings

High-twist contributions are retuned with scale changes depending on Q0 and x.

High-twist contribution to F2 is RS stable at small Q0 across x.

Alpha_s sensitivity to RS varies with Q0, being weaker at larger Q0.

Abstract

A sensitivity of twist-4 and $\alpha_s$ values extracted in the NLO QCD analysis of nonsinglet SLAC-BCDMS-NMC deep inelastic scattering data to the choice of QCD renormalization scale (RS) is analysed. It is obtained that the high twist (HT) contribution to structure function $F_2$, is retuned with the change of RS. This retuning depends on the choice of starting QCD evolution point $Q_0$ and x. At $Q_0 > 10 GeV^2$ the HT contribution to $F_2$ is retuned at small $x$ and almost not retuned at large $x$; at small $Q_0$ it exhibits approximate RS stability for all x in question. The HT contribution to $F_ L$ is RS stable for all $Q_0$ and x. The RS sensitivity of $\alpha_s$ also depends on the choice of $Q_0$: at large $Q_0$ this sensitivity is weaker, than at small one. For $Q_0^2=9 GeV^2$ the value $\alpha_s(M_Z)=0.1183\pm0.0021(stat+syst)\pm0.0013(RS)$ is obtained. Connection with the higher order QCD corrections is discussed.