Open charm hadroproduction and the charm content of the proton

We advocate charmed-hadron inclusive hadroproduction as a laboratory to probe intrinsic charm (IC) inside the colliding hadrons. Working at next-to-leading order in the general-mass variable-flavor-number scheme endowed with nonperturbative fragmentation functions recently extracted from a global fit to $e^{+}{e}^{-}$ annihilation data from KEKB, CESR, and LEP1, we first assess the sensitivity of Tevatron data of $D^0$, $D^{+}$, and $D^{*+}$ inclusive production to the IC parametrizations provided by Pumplin et al. We then argue that similar data from $pp$ collisions at RHIC would have the potential to discriminate between different IC models provided they reach out to sufficiently large values of transverse momentum.

Figure 1

$p_T$ distributions $d\sigma /d{p}_T$ of $p+\overline{p}\to X_c+X$ with (a) $X_c=D^0$, (b) $X_c=D^{+}$, and (c) $X_c=D^{*+}$ for $\sqrt{s}=1.96\mathrm{TeV}$ and $|y|<1$ evaluated at NLO in the GM-VFNS using the FFs of Ref. 13 in comparison with experimental data from CDF [1]. The solid lines represents the default predictions, for ${\xi }_R={\xi }_F=1$, and the dashed lines indicate the maximum deviations for independent variations in the range $1/2<{\xi }_R$, ${\xi }_F<2$.

Figure 2

Same as in Figs. 1a, 1b, 1c, but normalized to the default predictions.

Figure 3

Same as in Fig. 2a, but including besides the default prediction those evaluated with the IC parametrizations from Ref. 20 for $n=1$ (solid line), 2 (dashed line), 3 (densely dotted line), 4 (dot-dashed line), 5 (scarcely dotted line), and 6 (dotted line).

Figure 4

Same as in Figs. 1a, 3, but for $25\mathrm{GeV}<p_T<75\mathrm{GeV}$.

Figure 5

Same as in Fig. 1, but for $pp$ collisions with $\sqrt{s}=200\mathrm{GeV}$.

Figure 6

Same as in Fig. 3, but for $pp$ collisions with $\sqrt{s}=200\mathrm{GeV}$.

Figure 7

Same as in Figs. 5a, 6, but for $\sqrt{s}=500\mathrm{GeV}$.