Measurement of prompt D$^{0}$, $Λ_{c}^{+}$, and $Σ_{c}^{0,++}$(2455) production in pp collisions at $\sqrt{s} = 13$ TeV

Abstract

The $p_{\rm T}$-differential production cross sections of prompt D$^{0}$, $Λ_{\rm c}^{+}$, and $Σ_{\rm c}^{0,++}(2455)$ charmed hadrons are measured at midrapidity ($|y| < 0.5$) in pp collisions at $\sqrt{s} = 13$ TeV. This is the first measurement of $Σ_{\rm c}^{0,++}$ production in hadronic collisions. Assuming the same production yield for the three $Σ_{\rm c}^{0,+,++}$ isospin states, the baryon-to-meson cross section ratios $Σ_{\rm c}^{0,+,++}/{\rm D}^{0}$ and $Λ_{\rm c}^{+}/{\rm D}^{0}$ are calculated in the transverse momentum ($p_{\rm T}$) intervals $2 < p_{\rm T} < 12$ GeV/$c$ and $1 < p_{\rm T} < 24$ GeV/$c$. Values significantly larger than in e$^{+}$e$^{-}$ collisions are observed, indicating for the first time that baryon enhancement in hadronic collisions also extends to the $Σ_{\rm c}$. The feed-down contribution to $Λ_{\rm c}^{+}$ production from $Σ_{\rm c}^{0,+,++}$ is also reported and is found to be larger than in e$^{+}$e$^{-}$ collisions. The data are compared with predictions from event generators and other phenomenological models, providing a sensitive test of the different charm-hadronisation mechanisms implemented in the models.