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

Recent measurements for F-2(x,Q(2)) have been analyzed in terms of the dynamical and standard parton model approach at next-to-leading order (NLO) and next-to-next-to-leading order (NNLO) of perturbative QCD. Having fixed the relevant NLO and NNLO parton distributions, we present the implications and predictions for the longitudinal structure function F-L(x,Q(2)). It is shown that the previously noted extreme perturbative NNLO/NLO instability of F-L(x,Q(2)) is an artifact of the commonly utilized standard gluon distributions. In particular it is demonstrated that using the appropriate-dynamically generated-parton distributions at NLO and NNLO, F-L(x,Q(2)) turns out to be perturbatively rather stable already for Q(2)>= O(2-3 GeV2).