Charm production and hadronisation at the LHC with ALICE

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

Tuesday 3 Aug 2021, 11:00 → 12:00 Europe/Zurich

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.

https://arxiv.org/abs/2105.06335

20210803_CERNseminar_Jianhui_v13.pdf

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