Dynamical next-to-next-to-leading order parton distributions and the perturbative stability of FL(x,Q2)

It is shown that the previously noted extreme perturbative instability of the longitudinal structure function FL(x,Q2) in the small Bjorken-x region, is a mere artefact of the commonly utilized ‘standard’ gluon distributions. In particular it is demonstrated that using the appropriate – dynamically generated – parton distributions at NLO and NNLO, FL(x,Q2) turns out to be perturbatively rather stable already for Q2⩾O(2–3GeV2).