LHC Seminar

Charm production and hadronisation at the LHC with ALICE

by Jianhui Zhu (Central China Normal University CCNU (CN))

Video only

Video only


Charm quarks are produced in the early stage of interactions between colliding particles. The subsequent hadronisation of charm quarks into mesons or baryons occurs on a long space-time scale and was considered to be independent of the species of the colliding particles until the recent findings by the ALICE collaboration.

New measurements of charm-baryon production in proton-proton (pp) collisions at midrapidity by the ALICE collaboration show baryon-to-meson yield ratios much higher than those measured in $e^+e^-$ colliders and in ep collisions, suggesting that the charm fragmentation is not universal across different collision systems. Models that better reproduce the charm baryon-to-meson yield  ratios in pp collisions utilize enhanced color reconnection mechanisms or coalescence (recombination) schemes, or include significant contribution from heavier charm-baryon excited states decay. Furthermore, in heavy-ion collisions, the charm baryon-to-meson yield ratio is expected to be further enhanced if charm quarks hadronise via recombination with the surrounding light quarks in the quark-gluon plasma.

In this seminar, the $p_{\rm T}$-differential cross sections of $\Lambda_c^+$, $\Sigma_c^{0, ++}$, $\Xi_c^{0,+}$ baryons, the cross section times branching ratio of $\Omega_c^0$ baryon, the total charm cross section and charm fragmentation fractions in pp collisions at midrapidity are presented. These results are compared to the measurements in p-Pb and Pb-Pb collisions, and to theoretical model calculations.


Organized by

Michelangelo Mangano, Monica Pepe-Altarelli and Pedro Silva.

ALICE seminar - 3 august 2021
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