QCD effective charges and the structure function F2 at small-x: Higher twist effects

D Hadjimichef,E.G.S Luna,M Peláez

doi:10.1016/j.physletb.2020.135350

D Hadjimichef, E.G.S Luna + Show 1 more

Open Access

https://doi.org/10.1016/j.physletb.2020.135350

Copy DOI

Abstract

We consider the effect of higher twist operators of the Wilson operator product expansion in the structure function F2(x,Q2) at small-x, taking into account QCD effective charges whose infrared behavior is constrained by a dynamical mass scale. The higher twist corrections are obtained from the renormalon formalism. Our analysis is performed within the conventional framework of next-to-leading order, with the factorization and renormalization scales chosen to be Q2. The infrared properties of QCD are treated in the context of the generalized double-asymptotic-scaling approximation. We show that the corrections to F2 associated with twist-four and twist-six are both necessary and sufficient for a good description of the deep infrared experimental data.

Highlights

In the description of the structure function F2(x, Q2) of the proton, a long-standing question is the extent to which the nonperturbative properties of QCD affect the behavior of F2
We consider the effect of higher twist operators of the Wilson operator product expansion in the structure function F2(x, Q2) at small-x, taking into account QCD effective charges whose infrared behavior is constrained by a dynamical mass scale
By analyzing exclusively the small-x region, some of the simpler existing analytical solutions of the DGLAP evolution equation [13] in the small-x limit can be directly used [14–18]. Within this approach the F2 data at smallx can be interpreted in terms of the double-asymptoticscaling (DAS) phenomenon [14, 15], where small-x nucleon structure functions exhibit scaling in two new variables, provided only that the small-x behavior of the parton distribution functions (PDFs) at some starting point Q20 is sufficiently soft

Summary

INTRODUCTION

In the description of the structure function F2(x, Q2) of the proton, a long-standing question is the extent to which the nonperturbative properties of QCD affect the behavior of F2. By analyzing exclusively the small-x region, some of the simpler existing analytical solutions of the DGLAP evolution equation [13] in the small-x limit can be directly used [14–18] Within this approach the F2 data at smallx can be interpreted in terms of the double-asymptoticscaling (DAS) phenomenon [14, 15], where small-x nucleon structure functions exhibit scaling in two new variables, provided only that the small-x behavior of the parton distribution functions (PDFs) at some starting point Q20 is sufficiently soft. The resulting analytical solutions can in turn be extended in order to include the subasymptotic part of the DGLAP evolution [9, 10, 14, 19], in what is called GDAS approximation, leading to the prediction of flat forms at small-x for parton distributions at some input scale Q20, namely fa(x, Q20) = Aa (a = q, g) ,.

HIGHER TWIST OPERATORS

THE QCD EFFECTIVE CHARGE

RESULTS

CONCLUSIONS