Charm Hadrons in pp collisions at LHC energy within a Coalescence plus Fragmentation approach

Abstract

The recent experimental measurements on $pp$ collisions at $\sqrt{s}=5.02\mathrm{TeV}$ have shown a very large abundance of heavy baryon production corresponding to a ratio of ${\Lambda }_c/D^0\sim 0.6$, about one order of magnitude larger than what measured in $e^{+}{e}^{-}$, $ep$ collisions and even in $pp$ collisions at LHC, but at forward rapidity. We apply for the first time to $pp$ collisions a quark coalescence plus fragmentation approach developed for $AA$ collisions, assuming the formation of Hot QCD matter at finite temperature. An approach that has correctly predicted a ${\Lambda }_c/D\sim O(1)$ in AA collisions at RHIC energy. We calculate the heavy baryon/meson ratio and the $p_T$ spectra of charmed hadrons with and without strangeness content: $D^0$, $D_s$, ${\Lambda }_c^{+}$, ${\Xi }_c$ and ${\Omega }_c$ in $pp$ collisions at top LHC energies, finding a satisfactory result for the measured ${\Lambda }_c^{+}/D^0$ and the ${\Xi }_c/D^0$ without any specific tuning of parameters to $pp$ collisions. At variance with other approaches a coalescence approach predicts also a significant production of ${\Omega }_c$ such that ${\Omega }_c/D^0\sim O(10^{-1})$ .

Comments: 8 pages, 5 figures; modifications in Figures 1,2,3,4,5 and corrected typos