Speaker
Dr
Pedro Jimenez-Delgado
(Technische Universität Dortmund)
Description
Utilizing recent DIS measurements and Drell-Yan data we determine at NNLO (3-loop) of QCD the dynamical parton distribution functions of the nucleon generated radiatively from valencelike positive input distributions at an optimally chosen low resolution scale. These are compared with ``standard'' NNLO distributions generated from positive input distributions at some fixed and higher resolution scale. Although the NNLO corrections imply in both approaches an improved value of chi-square, present DIS data are still not sufficiently accurate to distinguish between NLO results and the minute NNLO effects of a few percent, despite of the fact that the dynamical NNLO uncertainties are somewhat smaller than the NLO ones and both are, as expected, smaller than those of their ``standard'' counterparts. The dynamical predictions for the longitudinal structure function of the proton become perturbatively stable already at Q^2 = 2-3 GeV^2 where precision measurements could even delineate NNLO effects in the very small-x region. This is in contrast to the common ``standard'' approach but NNLO/NLO differences are here less distinguishable due to the much larger uncertainty bands.
Primary author
Dr
Pedro Jimenez-Delgado
(Technische Universität Dortmund)
Co-author
Ewald Reya
(Technische Universität Dortmund)
