M. Glück

Dynamical parton distributions of the proton and small x physics

AbstractThe perturbative properties of parton distributions generated radiatively from a valence-like input at some low resolution scale are discussed with the aim of explaining the physical aspects underlying the reliability of the predicted distributions in the small-x region. Aspects of higher-twist (shadowing) effects as well as small-x resummations are discussed. Utilizing recent improved data atx≳10−2 and a factorization scheme in which the heavy quarksc, b, ..., arenot entailed among the intrinsic (massless) parton distributions, we readjust our valencelike input and provide parametrizations of the slightly modified dynamical LO and NLO

Next-to-leading order radiative parton model analysis of polarized deep inelastic lepton - nucleon scattering

(\overline {MS} ,DIS)

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

predictions for parton distributions.

Pionic parton distributions revisited

Recent data from deep inelastic scattering experiments atx≳10−2 are used to fix the parton distributions down tox⋟10−4 andQ2⋟0.3 GeV2. The predicted extrapolations are uniquely determined by the requirement of avalence-like structure ofall parton distributions at some low resolution scale and are furthermore shown to be insensitive in the small-x region, 10−4≲x≦10−2, to the detailed experimental input at the presently accessiblex>10−2. Simple parameterizations of the resulting parton distributions are presented in the range 10−5≲x<1 and 0.3≲Q2≲108 GeV2 as obtained from the leading- and higher-order evolution equations.

Heavy quarks at high energy colliders

A next-to-leading-order QCD analysis of spin asymmetries and structure functions in polarized deep inelastic lepton-nucleon scattering is presented within the framework of the radiative parton model. A consistent NLO formulation of the {ital Q}{sup 2} evolution of polarized parton distributions yields two sets of plausible NLO spin-dependent parton distributions in the conventional MS factorization scheme. They respect the fundamental positivity constraints down to the low resolution scale {ital Q}{sup 2}={mu}{sup 2}{sub NLO}=0.34 GeV{sup 2}. The {ital Q}{sup 2} dependence of the spin asymmetries {ital A}{sup {ital p},{ital n},{ital d}}{sub 1}({ital x},{ital Q}{sup 2}) is similar to the leading-order (LO) one in the range 1{le}{ital Q}{sup 2}{le}20 GeV{sup 2} and is shown to be non-negligible for {ital x} values relevant for the analysis of the present data and possibly forthcoming data at DESY HERA. {copyright} {ital 1996 The American Physical Society.}

Pionic parton distributions

The gluon and antiquark distributions of the nucleon are generated radiatively using the assumption that at some low resolution scale the nucleon consists entirely of valence quarks and valence-like gluons. The agreement between the uniquely predicted gluon and sea distributions and the available data on deep inelastic structure functions (including also recent low-Q2 measurements) and direct-photon production is demonstrated and discussed in detail. Simple parametrizations of the resulting (positive definite!) parton distributions are presented in the range 10−4≲x≦1 and 0.2≲Q2≲106 GeV2 as obtained according to the leading- and higher-order renormalization group evolution equations.

Comparing radiatively generated parton distributions with recent measurements of F2(x,Q2) in the small-x region

Utilizing recent DIS measurements (F2,L) and data on dilepton and high-ET 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(

The Strange Sea Density and Charm Production in Deep Inelastic Charged Current Processes

\overline{\text{MS}}