Measurement of the D⁺ -Meson Production Cross Section at Low Transverse Momentum in Pp¯ Collisions at √s =1.96 TeV

Le résumé fourni par la source

We report on a measurement of the $D^{+}$-meson production cross section as a\nfunction of transverse momentum ($p_T$) in proton-antiproton ($p\\bar{p}$)\ncollisions at 1.96 TeV center-of-mass energy, using the full data set collected\nby the Collider Detector at Fermilab in Tevatron Run II and corresponding to 10\nfb$^{-1}$ of integrated luminosity. We use $D^{+} \\to K^-\\pi^+\\pi^+$ decays\nfully reconstructed in the central rapidity region $|y|<1$ with transverse\nmomentum down to 1.5 GeV/$c$, a range previously unexplored in $p\\bar{p}$\ncollisions. Inelastic $p\\bar{p}$-scattering events are selected online using\nminimally-biasing requirements followed by an optimized offline selection. The\n$K^-\\pi^+\\pi^+$ mass distribution is used to identify the $D^+$ signal, and the\n$D^+$ transverse impact-parameter distribution is used to separate prompt\nproduction, occurring directly in the hard scattering process, from secondary\nproduction from $b$-hadron decays. We obtain a prompt $D^+$ signal of 2950\ncandidates corresponding to a total cross section $\\sigma(D^+, 1.5 < p_T <\n14.5~\\mbox{GeV/}c, |y|<1) = 71.9 \\pm 6.8 (\\mbox{stat}) \\pm 9.3\n(\\mbox{syst})~\\mu$b. While the measured cross sections are consistent with\ntheoretical estimates in each $p_T$ bin, the shape of the observed $p_T$\nspectrum is softer than the expectation from quantum chromodynamics. The\nresults are unique in $p\\bar{p}$ collisions and can improve the shape and\nuncertainties of future predictions.

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