Abstract
H1 and ZEUS have published single-differential cross sections for inclusive D ∗±-meson production in deep-inelastic ep scattering at HERA from their respective final data sets. These cross sections are combined in the common visible phase-space region of photon virtuality Q 2 > 5 GeV2, electron inelasticity 0.02 < y < 0.7 and the D ∗± meson’s transverse momentum p T(D ∗) > 1.5 GeV and pseudorapidity |η(D ∗)| < 1.5. The combination procedure takes into account all correlations, yielding significantly reduced experimental uncertainties. Double-differential cross sections d2 σ/dQ 2dy are combined with earlier D ∗± data, extending the kinematic range down to Q 2 > 1.5 GeV2. Perturbative next-to-leading-order QCD predictions are compared to the results.
Highlights
H1 and ZEUS have published single-differential cross sections for inclusive D∗±-meson production in deep-inelastic ep scattering at HERA from their respective final data sets
The combined single- and double-differential cross sections are presented in section 5 together with a comparison of NLO QCD predictions to the data
The data points removed from the combination mainly correspond to the low-y region where larger bins were used for the HERA-I data
Summary
The massive fixed-flavour-number scheme (FFNS) [25,26,27,28] is used for theoretical predictions, since it is the only scheme for which fully differential NLO calculations [29] are available. The cross-section predictions for D∗± production presented in this paper are obtained using the HVQDIS program [29] which provides NLO QCD (O(αs2)) calculations in the 3-flavour FFNS for charm and beauty production in DIS. The pole mass of the charm quark is set to mc = 1.50 ± 0.15 GeV This variation affects the values of the renormalisation and factorisation scales. The NLO calculation performed by the HVQDIS program yields differential cross sections for charm quarks These predictions are converted to D∗±-meson cross sections by applying the fragmentation model described in a previous publication [21]. The following parameters are used in the calculations together with the corresponding variations for estimating the uncertainties of the NLO predictions related to fragmentation:. The total theoretical uncertainties are obtained by adding all individual contributions in quadrature
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