München 2019 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 48: Heavy-Ion Collisions and QCD Phases IX

HK 48.6: Vortrag

Donnerstag, 21. März 2019, 15:30–15:45, HS 15

Production of (anti-)³He and (anti-)³H in p–Pb collisions at √s_NN=5.02 TeV measured with ALICE — •Sebastian Hornung for the ALICE collaboration — GSI Helmholtzzentrum für Schwerionenforschung, Darmstadt, Germany — Heidelberg University, Germany

The production mechanism of multi-baryon states in ultra-relativistic ion collisions is one of the open puzzles in high-energy physics. On the one hand, thermal-statistical hadronization models can describe the particle yields over a wide range of energies in AA collisions. On the other hand, the nuclei yields can also be explained by the coalescence of protons and neutrons which are close by in phase space. Studies of the light (anti-)nuclei production as a function of the charged-particle multiplicity per event provide an important insight into the system-size dependence of hadronization. Previous measurements in pp and Pb–Pb collisions by ALICE show a more coalescence-like behaviour for low multiplicities and a thermal behaviour at larger multiplicities.

The spectra of (anti-)³H and (anti-)³He measured in p–Pb collisions at √s_NN=5.02 TeV are presented. The latter were measured for different charged-particle multiplicities. Thanks to removal of the contamination from nuclei produced via spallation, the spectra could be evaluated down to a transverse momentum p_T = 1.5 GeV/c for both the anti-nuclei and the nuclei. These results contribute to the current picture by providing information about intermediate multiplicities. In addition, an upper limit on the production of anti-⁴He is provided.