Measurement of the D+ -meson production cross section at low transverse momentum in pp¯ collisions at s=1.96 TeV

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We report on a measurement of the ${D}^{+}$-meson production cross section as a function of transverse momentum (${p}_{T}$) in proton-antiproton ($p\overline{p}$) collisions at 1.96 TeV center-of-mass energy, using the full data set collected by the Collider Detector at Fermilab in Tevatron Run II and corresponding to $10\text{ }\text{ }{\mathrm{fb}}^{\ensuremath{-}1}$ of integrated luminosity. We use ${D}^{+}\ensuremath{\rightarrow}{K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$ decays fully reconstructed in the central rapidity region $|y|<1$ with transverse momentum down to $1.5\text{ }\text{ }\mathrm{GeV}/c$, a range previously unexplored in $p\overline{p}$ collisions. Inelastic $p\overline{p}$-scattering events are selected online using minimally biasing requirements followed by an optimized offline selection. The ${K}^{\ensuremath{-}}{\ensuremath{\pi}}^{+}{\ensuremath{\pi}}^{+}$ mass distribution is used to identify the ${D}^{+}$ signal, and the ${D}^{+}$ transverse impact-parameter distribution is used to separate prompt production, occurring directly in the hard-scattering process, from secondary production from $b$-hadron decays. We obtain a prompt ${D}^{+}$ signal of 2950 candidates corresponding to a total cross section $\ensuremath{\sigma}({D}^{+},1.5<{p}_{T}<14.5\text{ }\text{ }\mathrm{GeV}/c,|y|<1)=\phantom{\rule{0ex}{0ex}}71.9\ifmmode\pm\else\textpm\fi{}6.8(\mathrm{stat})\ifmmode\pm\else\textpm\fi{}9.3(\mathrm{syst})\text{ }\text{ }\ensuremath{\mu}\mathrm{b}$. While the measured cross sections are consistent with theoretical estimates in each ${p}_{T}$ bin, the shape of the observed ${p}_{T}$ spectrum is softer than the expectation from quantum chromodynamics. The results are unique in $p\overline{p}$ collisions and can improve the shape and uncertainties of future predictions.

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