Dynamical parton distributions of the nucleon and very small-x physics

TL;DR

This paper develops and compares dynamical and standard parton distribution functions of the nucleon using recent deep inelastic scattering and collider data, highlighting reduced uncertainties in the small-x region crucial for high-energy astrophysics.

Contribution

It introduces a radiative approach to determine dynamical parton distributions from valence-like inputs, showing improved precision over standard distributions, especially at very small-x.

Findings

Dynamical distributions have smaller uncertainties than standard ones.

Results are consistent with previous dynamical distributions within uncertainties.

Enhanced accuracy in small-x region for ultrahigh energy cross section calculations.

Abstract

Utilizing recent DIS measurements (F_{2,L}) and data on dilepton and high-E_{T} jet production we determine the dynamical parton distributions of the nucleon generated radiatively from valence-like positive input distributions at optimally chosen low resolution scales. These are compared with `standard' distributions generated from positive input distributions at some fixed and higher resolution scale. It is shown that up to the next to leading order NLO(\bar{MS}, DIS) of perturbative QCD considered in this paper, the uncertainties of the dynamical distributions are, as expected, smaller than those of their standard counterparts. This holds true in particular in the presently unexplored extremely small-x region relevant for evaluating ultrahigh energy cross sections in astrophysical applications. It is noted that our new dynamical distributions are compatible, within the presently determined uncertainties, with previously determined dynamical parton distributions.