Gießen 2024 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 21: Heavy-Ion Collisions and QCD Phases III

HK 21.5: Vortrag

Dienstag, 12. März 2024, 16:45–17:00, HBR 62: EG 03

Multiplicity dependence of prompt and non-prompt J/ψ production in pp collisions with ALICE — •Gauthier Legras for the ALICE Germany collaboration — Institut für Kernphysik, Universität Münster

J/ψ production involves a hard scale for the creation of the charm-anticharm pair, and a soft scale for its hadronization. Correlating it with the multiplicity, mainly produced by soft processes, in small systems allows to investigate the interplay between hard and soft scales. A stronger-than-linear multiplicity dependence of inclusive J/ψ in pp collisions was found in previous ALICE publications, but the main reason was not yet clearly identified, justifying the need for additional studies investigating its origin. For example, there could be different contributions between prompt (produced directly in the collision) and non-prompt (coming from the decay of beauty hadrons) J/ψ. Additionally, the multiplicity can be separated in different azimuthal regions relative to the J/ψ, and, in each region, different effects for particle production, due to correlation with the presence of a prompt or non-prompt J/ψ, could be isolated.

This study aims at determining the multiplicity dependence, the multiplicity being measured either inclusively at midrapidity or in three azimuthal regions, of prompt and non-prompt J/ψ production pp collisions at √s = 13 TeV, through its decay to an electron-positron pair at midrapidity. The rejection of background and separation between both J/ψ topologies is done with Boosted Decision Trees through the study of displaced decay vertices.