Köln 2025 – scientific programme
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HK: Fachverband Physik der Hadronen und Kerne
HK 19: Heavy-Ion Collisions and QCD Phases IV
HK 19.2: Talk
Tuesday, March 11, 2025, 16:00–16:15, HS 3 Chemie
Investigation of thermal and freeze-out contributions to the dilepton spectrum — •Jessica Ou Ya Vogel — TU Darmstadt
Measurements of dileptons emitted from heavy-ion collisions provide insights into the properties of the created fireball. As leptons are unaffected by the strong final-state interactions of the collision, they retain valuable information about the hot and dense medium formed during the heavy-ion reaction. The high baryon densities achieved in collisions at a few GeV induce significant medium effects on the spectral functions of vector mesons.
While short-lived ρ mesons predominantly decay within the fireball, radiating thermal dileptons, a substantial fraction of ω mesons decay outside the fireball due to their longer lifetime. These decays contribute to the freeze-out cocktail with the vacuum line shape of the vector mesons. High-statistics data from Ag+Ag collisions at √sNN = 2.55 GeV, measured by the HADES collaboration, may allow for the isolation of these two different contributions and enable studies of in-medium modifications of the ω meson spectral function in the experimental data.
This work presents a framework that describes the vector meson freeze-out contributions using the shining method, while the thermal dilepton spectrum is determined via the coarse-graining model. By combining these two approaches, we aim to achieve a precise theoretical description of the invariant mass spectrum of thermal dileptons in heavy-ion collisions within the few GeV energy range.
This work is supported by the DFG through grant CRC-TR 211.
Keywords: dilepton, hadronic matter, QGP, virtual photon