Measurement of D^(*+-) Meson Production and F_2^c in Deep-Inelastic Scattering at HERA
H1 Collaboration, C. Adloff
TL;DR
The study measures D*± production in deep-inelastic e+p scattering at HERA, extending the Q^2 range to 1 GeV^2 and using 18.6 pb^-1 of data. Differential and integrated cross sections are compared to HVQDIS (NLO DGLAP) and CASCADE (CCFM) predictions, revealing generally better agreement with CASCADE in several observables and underprediction by HVQDIS in forward regions. The charm contribution to the proton structure function, F2^c, is extracted by extrapolating the visible D* cross sections, showing F2^c rising rapidly with Q^2 and x and contributing up to >25% of F2 at high Q^2. The results illustrate the importance of evolution dynamics (DGLAP vs. CCFM) and fragmentation modeling in describing open charm production and its role in constraining the gluon density in the proton.
Abstract
The inclusive production of D^{*+-}(2010) mesons in deep-inelastic scattering is studied with the H1 detector at HERA. In the kinematic region 1<Q^2<100 GeV^2 and 0.05<y<0.7 an e^+p cross section for inclusive D^(*+-) meson production of 8.50+- 0.42 (stat.)^(+1.21)_(-1.00) (syst.) nb is measured in the visible range p_(tD^*)>1.5 GeV and |η_(D^*)|<1.5. Single and double differential inclusive D^(*+-) meson cross sections are compared to perturbative QCD calculations in two different evolution schemes. The charm contribution to the proton structure, F_2^c(x,Q^2), is determined by extrapolating the visible charm cross section to the full phase space. This contribution is found to rise from about 10% at Q^2 = 1.5 GeV^2 to more than 25% at Q^2 = 60 GeV^2 corresponding to x values ranging from 5*10^(-5) to 3*10^(-3)$.