Charm production and hadronization in pp and p-Pb collisions at the LHC with ALICE

TL;DR

This paper investigates charm-quark hadronization in pp and p-Pb collisions at the LHC using ALICE data, revealing differences from e+e- collisions and exploring potential nuclear matter effects on hadronization.

Contribution

It provides the first measurements of charm baryon-to-meson ratios at low transverse momentum in pp and p-Pb collisions, highlighting differences in fragmentation fractions from previous e+e- data.

Findings

Fragmentation fractions differ from e+e- measurements.

First measurement of $ m \Lambda_c^+ / D^0$ ratio at low pT.

Possible modification of hadronization in p-Pb due to nuclear effects.

Abstract

Studies of open-charm hadron production in pp and \pPb collisions are performed by the ALICE Collaboration at the LHC to investigate charm-quark hadronization mechanisms. Recent measurements of charm meson (${\rm D^0}$, ${\rm D^+}$, ${\rm D^+_{\rm s}}$, and ${\rm D^{*+}}$) and baryon ($\Lambda^+_{\rm c}$, $\Xi^{0,+}_{\rm c}$, $\Sigma^{0,++}_{\rm c}$, and $\Omega^0_{\rm c}$) production in pp collisions at $\sqrt{s}$ = 5.02 TeV and $\sqrt{s}$ = 13 TeV allow the determination of the charm cross section and the fragmentation fractions at $\sqrt{s}$ = 5.02 TeV with unprecedented precision. The measurements show that the fragmentation fractions significantly differ from the ones measured in ${\rm e^+e^-}$ and \ep collisions. This highlights possible differences in the hadronization process between electron induced collisions and pp collisions at the LHC. \\ Furthermore, the first measurement of the baryon-to-meson yield ratio $\Lambda^+_{\rm c}/{\rm D^0}$, down to $p_{\rm T}=0$ in pp and \pPb collisions will be discussed. In p--Pb collisions a modification of the hadronization mechanisms could be present due to cold nuclear matter effects and collective phenomena. A systematic comparison between data and model calculations will help to understand charm quark hadronization in pp and p--Pb collisions.