SMuK 2023 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 65: Heavy-Ion Collisions and QCD Phases XII
HK 65.5: Talk
Thursday, March 23, 2023, 16:45–17:00, SCH/A216
Topological separation of dielectron signals in Pb–Pb collisions with ALICE — •Jerome Jung for the ALICE Germany collaboration — Institut für Kernphysik, Goethe-Universität Frankfurt
Dielectrons are an exceptional tool to study the evolution of the medium created in heavy-ion collisions. In central collisions, the energy densities are sufficient to create a quark-gluon plasma (QGP). Thermal e+e− pairs with invariant mass around 1.5 GeV/c2 can be used to estimate the temperature of the QGP.
At LHC energies, correlated HF hadron decays dominate the dielectron yield for invariant masses above 1.1 GeV/c2. Their contribution is modified in the medium compared to elementary collisions to an unknown extent, leading to large uncertainties in the subtraction of known hadronic sources. The proper decay length of HF hadrons is of the order of cτ ≈ 100−500 µm, hence their reconstructed decay electrons do not point to the primary vertex of the collision. Therefore, a topological separation based on the distance-of-closest approach (DCA) to the primary vertex is a promising alternative approach to disentangle them from the prompt contribution of thermal dielectrons.
In this talk, the newest results on the DCAee spectra of dielectrons produced in Pb–Pb collisions at √sNN=5.02 TeV with ALICE will be presented. The measurements are compared to reference distributions from simulations and expectations from theory. The presentation will conclude with a discussion of novel developments of the dielectron analysis.