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

TL;DR

This paper applies a coalescence plus fragmentation model, originally for heavy-ion collisions, to proton-proton collisions at LHC energies, successfully explaining the large observed heavy baryon production ratios.

Contribution

It introduces a novel application of a coalescence plus fragmentation approach to $pp$ collisions, accurately predicting heavy baryon/meson ratios without parameter tuning.

Findings

Reproduces the measured $ ext{Lambda}_c^+/D^0$ ratio in $pp$ collisions.

Predicts significant $ ext{Omega}_c$ production with $ ext{Omega}_c/D^0 ext{~O}(10^{-1})$.

Provides $p_T$ spectra for various charmed hadrons in $pp$ collisions.

Abstract

The recent experimental measurements on $pp$ collisions at $\sqrt{s}=5.02 \,\rm TeV$ 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 $\Omega_c/D^0 \sim O(10^{-1})$ .