CiteWeb id: 19990000273

CiteWeb score: 2955

DOI: 10.1007/s100529900196

An up-to-date global QCD analysis of high energy lepton-hadron and hadron-hadron interactions is performed to better determine the gluon and quark parton distributions in the nucleon. Improved experimental data on inclusive jet production, in conjunction with precise deep inelastic scattering data, place good constraints on the gluon over a wide range of x; while new data on asymmetries in Drell-Yan processes contribute to better determine the d=u ratio. Comparisons with results of other recent global analyses are made, and the dierences are described. Open issues and the general problem of determining the uncertainties of parton distributions are discussed. The structure of hadrons represented by parton distribu- tions is an essential part of our knowledge of the elemen- tary particle physics world. The interpretation of existing experimental data in terms of the Standard Model (SM), the precision measurements of SM parameters, as well as the direct search for signals for physics beyond the SM, all rely heavily on calculations based on Quantum Chromo- dynamics (QCD) and the QCD-parton picture, with the parton distribution (and fragmentation) functions as es- sential input. The (non-perturbative) parton distribution functions at some given momentum scale are currently determined phenomenologically by a global analysis of a wide range of available hard scattering processes involving initial-state hadrons, using the perturbative QCD-parton framework. The global analysis of parton distributions requires a continuing eort. As new experimental and theoretical ad- vances occur, the parton distributions can be determined with increasing accuracy and assurance. Although current knowledge of the parton distributions, based on several generations of global analyses, is far more quantitative than in the early years of the parton model, gaps still remain, as will be discussed at the end of this paper. In addition to lling these gaps, there are two important mo- tivations for the vigorous pursuit of global analysis: (i) a comprehensive global analysis constitutes an important ? This work is partially supported by NSC (Taiwan), and