A combination is presented of the inclusive deep inelastic cross sections measured by the H1 and ZEUS Collaborations in neutral and charged current unpolarised e ± p scattering at HERA during the period 1994-2000. The data span six orders of magnitude in negative four-momentum-transfer squared, Q 2 , and in Bjorken x. The combination method used takes the correlations of systematic uncertainties into account, resulting in an improved accuracy. The combined data are the sole input in a NLO QCD analysis which determines a new set of parton distributions, HERAPDF1.0, with small experimental uncertainties. This set includes an estimate of the model and parametrisation uncertainties of the fit result.

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Charged particle multiplicity distributions in positron-proton deep inelastic scattering at a centre-of-mass energy $$\sqrt{s}=319$$ s = 319  GeV are measured. The data are collected with the H1 detector at HERA corresponding to an integrated luminosity of 136  pb$$^{-1}$$ - 1 . Charged particle multiplicities are measured as a function of photon virtuality $$Q^2$$ Q 2 , inelasticity y and pseudorapidity $$\eta $$ η in the laboratory and the hadronic centre-of-mass frames. Predictions from different Monte Carlo models are compared to the data. The first and second moments of the multiplicity distributions are determined and the KNO scaling behaviour is investigated. The multiplicity distributions as a function of $$Q^2$$ Q 2    and the Bjorken variable $$x_{\mathrm{bj}}$$ x bj are converted to the hadron entropy $$S_{\mathrm{hadron}}$$ S hadron , and predictions from a quantum entanglement model are tested.

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