SMuK 2023 – wissenschaftliches Programm

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HK: Fachverband Physik der Hadronen und Kerne

HK 47: Heavy-Ion Collisions and QCD Phases X

HK 47.5: Vortrag

Mittwoch, 22. März 2023, 18:30–18:45, SCH/A315

Net-Proton Fluctuations in Pb-Pb Collisions with the ALICE Experiment — •Ilya Fokin for the ALICE Germany collaboration — Physikalisches Institut, Heidelberg

Fluctuations of conserved charges -- such as the electric charge, baryon number or strangeness -- in ultrarelativistic heavy-ion collisions provide insight into the QCD phase diagram. They are quantified using moments or cumulants of the distribution of the respective charge in a collision, which can be related to susceptibilities from lattice QCD calculations. These numerical calculations predict a second order phase transition from the quark-gluon plasma to the hadron gas close to the chemical freeze-out temperature for vanishing quark masses and baryon chemical potential, which is expected to turn into a continuous crossover for physical masses. Since the LHC provides heavy-ion collisions with almost vanishing baryon chemical potential, using the proton number as a proxy for the baryon number makes the lattice QCD results accessible in the experiment.

In this contribution, recent measurements of higher-order cumulants of the net-proton number in Pb-Pb collisions recorded with the ALICE detector are presented. Their dependence on the pseudorapidity acceptance and centrality and comparisons to models are discussed. Moments of the proton number distributions are measured probabilistically using the Identity Method, treating contamination of the proton sample in a natural way.