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HK: Fachverband Physik der Hadronen und Kerne
HK 9: Heavy-Ion Collisions and QCD Phases II
HK 9.1: Group Report
Monday, March 11, 2024, 16:45–17:15, HBR 62: EG 05
Characterising the hot and dense fireball with virtual photons at HADES — •Niklas Schild for the HADES collaboration — TU Darmstadt, Darmstadt, Germany
The High-Acceptance-Di-Electron-Spectrometer (HADES) at GSI, Darmstadt, measures heavy-ion and elementary collisions at a few GeV beam energies, enabling the investigation of nuclear matter at high densities and moderate temperatures. One pillar of HADES is the study of these collisions not only through hadrons, which are heavily affected by freeze-out stages, but also via rare electromagnetic probes, as they allow unique insights into the evolution of the collision throughout. In particular, virtual photons, decaying into e+e− pairs, encode numerous characteristics of the fireball and deliver additional information in their invariant mass.
In this contribution, we present measurements of such dileptons collected in heavy-ion Ag+Ag and Au+Au as well as elementary p+p collisions at √sNN=2.55 GeV and √sNN=2.42 GeV. Combination of these HADES data sets brings a unique opportunity to gain new insights into the dilepton excess and its dependence on system size and centrality. Hence, we provide an overview of recent works and progress in the dilepton analysis at HADES. This includes advances in the particle identification, multidifferential dilepton spectra as well as studies on collectivity via the investigation of anisotropic flow and polarisation.
This work has been supported by BMBF (05P18RDFC1), GSI F&E, HGS-HIRe, HFHF and ELEMENTS (500/10.006).
Keywords: HADES; Heavy-Ion Collisions; Electromagnetic Probes; Dileptons; GSI