The HERAPDF project aims to extract quark and gluon parton distribution functions (PDFs) of the proton from experimental data. The HERA deep inelastic scattering data provide some of the strongest constraints on PDFs and particularly for the gluon density at low x which is essential for predictions of Higgs boson production rates. In addition the final HERA data have now been published by H1 and ZEUS and provide more flavour discrimination with better precision in the high x region, which is relevant for predicting new physics models at high energy.
The project has developed a statisitical combination method to optimise the averaging of H1 and ZEUS measurements in a model independent way which also accounts for correlated systematic uncertainties allowing allowing cross-calibration to reduce the overall systematic uncertainty on the combined data. The averaged data are then used in a QCD fit to determine the proton PDFs with a complete evaluation of the experimental and theoretical uncertainties.
The next phase of the project will
Combined Measurement and QCD Analysis of the Inclusive ep Scattering Cross Sections at HERAH1 and Zeus Collab., Dr Eram Rizvi et.al.,JHEP 2009 (arXiv:0911.0884)
Combination of Measurements of Inclusive Deep Inelastic ep Scattering Cross Sections and QCD Analysis of HERA DataH1 and Zeus Collab., Dr Eram Rizvi et.al.,Eur.Phys.J. C75 (2015) 12, 580