Combination of measurements of inclusive deep inelastic ${e^{\pm }p}$ scattering cross sections and QCD analysis of HERA data

A combination is presented of all inclusive deep inelastic cross sections previously published by the H1 and ZEUS collaborations at HERAfor neutral and charged currente±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, Q2, 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 partondistribution functions, called HERAPDF2.0. In addition to the experimental uncertainties, modeland parameterisation uncertainties were assessed for these partondistribution 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 HERAdata on charm and jet production, resulting in the variant HERAPDF2.0Jets. The inclusion of jet-production cross sections made a simultaneous determination of these partondistributions and the strong coupling constant possible, resulting in αs(MZ)=0.1183±0.0009(exp)±0.0005(model/parameterisation)±0.0012(hadronisation)+0.0037−0.0030(scale). An extraction of xFγZ3 and results on electroweak unification and scaling violations are also presented.