Abstract
A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERA for neutral and charged current e(+/-)p scattering for zero beam polarisation. The data were taken at proton beam energies of 920, 820, 575 and 460 GeV and an electron beam energy of 27.5 GeV. The data correspond to an integrated luminosity of about 1 fb(-1) and span six orders of magnitude in negative four-momentum-transfer squared, Q(2), and Bjorken x. The correlations of the systematic uncertainties were evaluated and taken into account for the combination. The combined cross sections were input to QCD analyses at leading order, next-to-leading order and at next-to-next-to-leading order, providing a new set of parton distribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, model and parameterisation uncertainties were assessed for these parton distribution functions. Variants of HERAPDF2.0 with an alternative gluon parameterisation, HERAPDF2.0AG, and using fixed-flavour-number schemes, HERAPDF2.0FF, are presented. The analysis was extended by including HERA data on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jet-production cross sections made a simultaneous determination of these parton distributions and the strong coupling constant possible, resulting in as alpha(s) (M-Z(2)) = 0.1183 +/- 0.0009(exp) +/- 0.0005(model/parameterisation) +/- 0.0012(hadronisation)(-0.0030)(+0.0037)(scale). An extraction of xF(3)(gamma Z) and results on electroweak unification and scaling violations are also presented.
| Original language | English |
|---|---|
| Article number | 580 |
| Pages (from-to) | 1-98 |
| Number of pages | 98 |
| Journal | European Physical Journal C |
| Volume | 75 |
| Issue number | 12 |
| DOIs | |
| Publication status | Published - 8 Dec 2015 |
Funding
We are grateful to the HERA machine group whose outstanding efforts have made these experiments possible. We appreciate the contributions to the construction, maintenance and operation of the H1 and ZEUS detectors of many people who are not listed as authors. We thank our funding agencies for financial support, the DESY technical staff for continuous assistance and the DESY directorate for their support and for the hospitality they extended to the non-DESY members of the collaborations. We would like to give credit to all partners contributing to the EGI computing infrastructure for their support.
All Science Journal Classification (ASJC) codes
- Engineering (miscellaneous)
- Physics and Astronomy (miscellaneous)