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

Abstract

A combination is presented of all inclusive deep
\ninelastic cross sections previously published by the H1 and
\nZEUS collaborations at HERA for neutral and charged current e± p scattering for zero beam polarisation. The datawere
\ntaken at proton beam energies of 920, 820, 575 and 460GeV
\nand an electron beam energy of 27.5GeV. The data correspond
\nto an integrated luminosity of about 1 fb−1 and span
\nsix orders ofmagnitude in negative four-momentum-transfer
\nsquared, Q2, and Bjorken x. The correlations of the systematic
\nuncertainties were evaluated and taken into account for
\nthe combination. The combined cross sections were input
\nto QCD analyses at leading order, next-to-leading order and
\nat next-to-next-to-leading order, providing a new set of parton
\ndistribution functions, called HERAPDF2.0. In addition
\nto the experimental uncertainties, model and parameterisation
\nuncertainties were assessed for these parton distribution
\nfunctions. Variants of HERAPDF2.0 with an alternative
\ngluon parameterisation, HERAPDF2.0AG, and using fixedflavour-
\nnumber schemes, HERAPDF2.0FF, are presented.
\nThe analysiswas extended by includingHERAdata on charm
\nand jet production, resulting in the variant HERAPDF2.0Jets.
\nThe inclusion of jet-production cross sections made a simultaneous
\ndetermination of these parton distributions and the
\nstrong coupling constant possible, resulting in αs (M2Z
\n) =
\n0.1183±0.0009(exp)±0.0005(model/parameterisation)±
\n0.0012(hadronisation)
\n+0.0037
\n−0.0030(scale).An extraction of xFγ Z
\n3
\nand results on electroweak unification and scaling violations
\nare also presented.