Speaker
Description
Charm quarks are a powerful probe of the Quark-Gluon Plasma (QGP) formed in
high- energy heavy-ion collisions. Produced in hard scattering processes on a
timescale shorter than the QGP formation time, they experience the whole evolution
of the medium interacting with its constituents. The measurements of charm-hadron
production allows testing the mechanisms of in-medium parton energy loss. Moreover,
the study of charm-baryon production in heavy-ion collisions and in particular the
baryon-to-meson ratio, provides unique information on hadronisation mechanisms,
constraining the role of coalescence and testing the predicted presence of
diquark states in the medium. In particular, the $\Lambda_c/\rm D^0$ ratio is
expected to be enhanced with respect to the proton-proton baseline if charm quarks
hadronise via recombination with the surrounding light quarks in the QGP. In this
scenario, the presence of diquark bound states in the QGP could further increase
the $\Lambda_c$ production. Thus, charm baryons are ideal tools to investigate
unexplored aspects of the QGP. The ALICE detector is well suited to detect charm
baryons down to low $p_{\rm T}$ thanks to the excellent tracking capabilities and
state-of-art particle identification. In pp and Pb-Pb collisions, $\Lambda_c$ baryons
are reconstructed in the hadronic decay channels $\Lambda_c\rightarrow pK^0_s$ and
$\Lambda_c\rightarrow pK\pi$ by means of machine-learning methods.
In this contribution, the new ALICE results on charm-meson and baryon production
from the 2018 Pb-Pb sample and from the 2017 pp sample will be shown. In the pp system,
the measurement of $\Lambda_c$ production as a function of charged-particle multiplicity
will be discussed. In the Pb-Pb system, the measurement of the $\Lambda_c$ production, n
uclear modification factor and the $\Lambda_c/\rm D^0$ ratio in central and
semi-central events in a large transverse-momentum interval
($2 \le p_{\rm T} \le 24$ GeV/$c$) will be discussed together with the comparison
with similar results in smaller collision systems. Moreover, the comparison of our
results to theoretical models will be shown.
Finally, we will discuss the status and prospects for the $\Xi_c$ and $\Sigma_c$ analyses.
