The nuclear dependence for 800 GeV/c proton production of neutron D mesons has been measured near xF=0 in Experiment 789 at Fermilab. D mesons from beryllium and gold targets were detected with a pair spectrometer and a silicon vertex detector via their decay D→Kπ. No nuclear dependence is found, with a measured α=1.02±0.03±0.02. The measured differential cross section, dσ/dxF, for neutral-D-meson production at 〈xF〉=0.031 is 58±3±7 μb/nucleon. The integrated cross section obtained by extrapolation of the measured cross section to all xF is 17.7±0.9±3.4 μb/nucleon and is consistent with previous measurements.
We measure the neutral D total forward cross section and the differential cross sections as function of Feynman-x ($x_F$) and transverse momentum squared for 500 GeV/c $\pi^-$-nucleon interactions. The results are obtained from 88990+-460 reconstructed neutral D mesons from Fermilab experiment E791 using the decay channels $D\to K^-\pi^+$ and $D\to K^-\pi^+\pi^-\pi^+$ (and charge conjugates). We extract fit parameters from the differential cross sections and provide the first direct measurement of the turnover point in the $x_F$ distribution, 0.0131+-0.0038. We measure an absolute $D^0 + \bar{D^0}$ ($x_F > 0$) cross section of 15.4+1.8-2.3 microbarns/nucleon (assuming a linear A dependence). The differential and total forward cross sections are compared to theoretical predictions and to results of previous experiments.
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