NA49 Energy Scan Results for Central Lead-Lead Collisions at the CERN SPS

The energy dependence of hadron production in central Pb-Pb collisions at SPS energies is presented and compared with data at lower and higher energies and with results from p-p interactions. It is observed that there is little change in transverse activity in the SPS energy range, that there is a steepening rate of increase of pion production and that the K+/pi+ ratio exhibits a sharp peak located at about 30 AGeV. The Lambda/pi ratio also shows a pronounced maximum which is weaker in Ksi/pi and absent in Omega/pi.Comment: To appear in the proceedings of the 39th Rencontres de Moriond on QCD and High-Energy Hadronic Interactions, La Thuile, March 28 - April 4, 200

Future measurements of alpha_s and xg from scaling violations at HERA

Results are presented of a study of the experimental and theoretical accuracy one may achieve at HERA in measuring the strong coupling constant alpha_s and the gluon distribution from scaling violations of F2 structure functions.Comment: 7 pages, 2 figures. Latex source file and 2 separate .ps files. Talk presented at the DIS97 workshop, Chicago, April 14-18 199

QCDNUM: Fast QCD Evolution and Convolution

The QCDNUM program numerically solves the evolution equations for parton densities and fragmentation functions in perturbative QCD. Un-polarised parton densities can be evolved up to next-to-next-to-leading order in powers of the strong coupling constant, while polarised densities or fragmentation functions can be evolved up to next-to-leading order. Other types of evolution can be accessed by feeding alternative sets of evolution kernels into the program. A versatile convolution engine provides tools to compute parton luminosities, cross-sections in hadron-hadron scattering, and deep inelastic structure functions in the zero-mass scheme or in generalised mass schemes. Input to these calculations are either the QCDNUM evolved densities, or those read in from an external parton density repository. Included in the software distribution are packages to calculate zero-mass structure functions in un-polarised deep inelastic scattering, and heavy flavour contributions to these structure functions in the fixed flavour number scheme.Comment: 74 pages, 6 figures. Minor modifications in the text and updated list of reference

Error Estimates on Parton Density Distributions

Error estimates on parton density distributions are presently based on the traditional method of least squares minimisation and linear error propagation in global QCD fits. We review the underlying assumptions and the various mathematical representations of the method and address some technical issues encountered in such a global analysis. Parton distribution sets which contain error information are described.Comment: Latex, 12 pages, 5 figures. Needs iopart.cls and iopart12.clo. Presented at New Trends in HERA Physics 2001, Ringberg Castle, Tegernsee, Germany, June 17-22, 200

QCD fits to ZEUS and fixed target structure function data

Preliminary results are presented on the gluon density obtained from a QCD analysis of ZEUS and NMC F2 structure function data. Also given is an estimate of the experimental error on the positron-proton NC Born cross-section at large x and Q2.Comment: 6 pages, 3 figures. Latex source file and 3 separate .eps files. Talk presented at the DIS97 workshop, Chicago, April 14-18 199

The t-tbar cross-section at 1.8 and 1.96 TeV: a study of the systematics due to parton densities and scale dependence

We update the theoretical predictions for the t-tbar production cross-section at the Tevatron, taking into account the most recent determinations of systematic uncertainties in the extraction of the proton parton densities.Comment: 12 pages, 1 figure, Late

A QCD analysis of HERA and fixed target structure function data

The parton momentum densities in the proton are obtained from a NLO QCD analysis of structure functions measured by HERA and fixed target experiments. The uncertainties in these parton densities, the structure functions and related cross sections are estimated from the experimental errors, taking into account all correlations. Standard Model predictions for the charged current Born cross sections at large x and Q2 are calculated and compared with recent data from ZEUS.Comment: 4 pages LaTeX, 5 eps figures, uses npb.sty. Presented at DIS99, Zeuthen, Germany, April 19-23, 199