Asymmetries between the production of Ds− and Ds+ mesons from 500 GeV/c π− nucleon interaction as functions of xF and pt2

We present measurements of the production of Ds− mesons relative to Ds+ mesons as functions of xF and of pt2 for a sample of 2445 Ds decays to φπ. The Ds mesons were produced in Fermilab experiment E791 with 500 GeV/c π− mesons incident on one platinum and four carbon foil targets. The acceptance-corrected integrated asymmetry in the xF range −0.1 to 0.5 for Ds± mesons is 0.032 ± 0.022 ± 0.022, consistent with no net asymmetry. We compare the results as functions of xF and pt2 to predictions and to the large production asymmetry observed for D± mesons in the same experiment. These comparisons support the hypothesis that production asymmetries come from the fragmentation process and not from the charm quark production itself.