Prompt charm production in $pp$ collisions at $\sqrt{s}$ = 7 TeV

Charm production at the LHC in $pp$ collisions at $\sqrt{s}$ = 7 TeV is studied with the LHCb detector. The decays $D^0 \rightarrow K^- \pi^+$, $D^+ \rightarrow K^- \pi^+ \pi^+$, $D^{*+} \rightarrow D^0(K^- \pi^+) \pi^+$, $D^+_{\mathrm{s}} \rightarrow \phi(K^- K^+) \pi^+$, $\Lambda_{\mathrm{c}}^+ \rightarrow p K^- \pi^+$, and their charge conjugates are analysed in a data set corresponding to an integrated luminosity of 15 nb$^{-1}$. Differential cross-sections d$\sigma$ / d$p_{\rm T}$ are measured for prompt production of the five charmed hadron species in bins of transverse momentum and rapidity in the region 0 < $p_{\rm T}$ < 8 GeV$c$ and 2.0 < $y$ < 4.5. Theoretical predictions are compared to the measured differential cross-sections. The integrated cross-sections of the charm hadrons are computed in the above $p_{\rm T}$-$y$ range, and their ratios are reported. A combination of the five integrated cross-section measurements gives \begin{equation*} \sigma(c\overline{c})_{p_{\rm T} < 8 \mathrm{GeV/}c, 2.0 < y < 4.5} = 1419 \pm 12 \mathrm{(stat)} \pm 116 \mathrm{(syst)} \pm 65 \mathrm{(frag)}\mathrm{\mu b}, \end{equation*} where the uncertainties are statistical, systematic, and due to the fragmentation functions.