Abstract
Measurements of open charm and beauty production cross sections in deep inelastic ep scattering at HERA from the H1 and ZEUS Collaborations are combined. Reduced cross sections are obtained in the kinematic range of negative four-momentum transfer squared of the photon 2.5~hbox {GeV}^2le Q^2 le 2000, hbox {GeV}^2 and Bjorken scaling variable 3 cdot 10^{-5} le x_mathrm{Bj} le 5 cdot 10^{-2}. The combination method accounts for the correlations of the statistical and systematic uncertainties among the different datasets. Perturbative QCD calculations are compared to the combined data. A next-to-leading order QCD analysis is performed using these data together with the combined inclusive deep inelastic scattering cross sections from HERA. The running charm- and beauty-quark masses are determined as m_c(m_c) = 1.290^{+0.046}_{-0.041} mathrm{(exp/fit)}{}^{+0.062}_{-0.014} mathrm{(model)}{}^{+0.003}_{-0.031} mathrm{(parameterisation)} GeV and m_b(m_b) = 4.049^{+0.104}_{-0.109} mathrm{(exp/fit)}{}^{+0.090}_{-0.032} mathrm{(model)}{}^{+0.001}_{-0.031} mathrm{(parameterisation)}~mathrm{GeV}.
Highlights
Measurements of open charm and beauty production in neutral current (NC) deep inelastic electron1–proton scattering (DIS) at HERA provide important input for tests of the theory of strong interactions, quantum chromodynamics (QCD)
The parameterisation uncertainty is determined at each xBj value from the maximal differences between the parton distribution functions (PDFs) resulting from the central fit and all parameterisation variations
Measurements of charm and beauty production cross sections in deep inelastic ep scattering by the H1 and ZEUS experiments are combined at the level of reduced cross sections, accounting for their statistical and systematic correlations
Summary
Measurements of open charm and beauty production in neutral current (NC) deep inelastic electron1–proton scattering (DIS) at HERA provide important input for tests of the theory of strong interactions, quantum chromodynamics (QCD). The cross section depends strongly on the gluon distribution in the proton and the heavy-quark mass This mass provides a hard scale for the applicability of perturbative QCD (pQCD). A simultaneous combination of charm and beauty production cross-section measurements is presented. A single consistent dataset from HERA of reduced charm and beauty cross sections in DIS is obtained, including all correlations. This dataset covers the kinematic range of photon virtuality 2.5 GeV2 ≤ Q2 ≤ 2000 GeV2 and Bjorken scaling variable 3 · 10−5 ≤ xBj ≤ 5 · 10−2. The combined reduced charm cross sections of the previous analysis [42] are superseded by the new results presented in this paper.
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