The HERA Proton

Abstract

The almost 1 fb −1 of ep data collected by the H1 and ZEUS collider exper- iments at HERA allows for a precise determination of the proton's parton distribution functions (PDFs). Measurements used to constrain the PDFs — inclusive and jet cross sections, charm contribution to the F2 proton structure function, F c¯ c 2 — are presented herein. The measurement process itself includes cataloguing the sensitivity of the cross sections to the various sources of correlated systematic uncertainties. In the jet measure- ment, correlations of a statistical nature are also quantified and catalogued. These corre- lations provide a basis to combine measurements of the same physical observable across different time periods, experiments and measurement methodology. The subsequent PDF fitting procedure also takes into account such correlations. The resulting HERAPDF1.5 set based on inclusive data as well as PDF sets derived from inclusive plus charm data are presented togeteher with their predictions for pp cross sections at the LHC.