On the x-Independence of the {{R}^{Q}} = F_{L}^{Q}{text{/}}F_{2}^{Q} Ratio at Low x

Abstract

We give predictions for the ratio {{R}^{Q}}(x,{{Q}^{2}}) = F_{L}^{Q}(x,{{Q}^{2}}){text{/}}F_{2}^{Q}(x,{{Q}^{2}}) at small values of Bjorken variable x in the first three orders of perturbation theory. We show an approximate x-independence of {{R}^{Q}}(x,{{Q}^{2}}) at low x and non-large {{Q}^{2}} values ({{Q}^{2}} leqslant 8{-} 10m_{Q}^{2}), irrespectively on the gluon density in a proton used in the calculations. This observation could be useful in subsequent phenomenological studies of the heavy flavor production at future lepton–hadron and hadron–hadron colliders.