München 2019 – wissenschaftliches Programm
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HK: Fachverband Physik der Hadronen und Kerne
HK 26: Heavy-Ion Collisions and QCD Phases V
HK 26.3: Vortrag
Dienstag, 19. März 2019, 17:15–17:30, HS 15
Azimuthal Anisotropy of Virtual Photons — •Dominique Dittert for the HADES collaboration — TU Darmstadt
Virtual photons, that decay into dileptons, are penetrating probes which directly access the entire space-time-evolution of the fireball and escape from the collision zone without further interactions. Thus they provide unique information about the various stages of the collision. Collective observables like flow are used to describe the macroscopic properties of nuclear matter. Since the effective temperature extracted from the mT spectra of dileptons results from the superposition of all fireball stages with decreasing temperature T but increasing radial flow over time, it is difficult to disentangle early and late emission sources. In comparison, the elliptic flow does not show this implicit time dependence and the combined dependence of elliptic flow of dileptons on their transverse momentum and their invariant mass provides a rich landscape of structures, which allows to set the observational window on specific stages of the fireball evolution. In this contribution the preliminary results on azimuthal anisotropy of e+e− excess radiation measured in Au+Au collisions at √sNN = 2.4 GeV with HADES will be presented.