Speaker
Description
The High Acceptance Di-Electron Spectrometer (HADES) experiment has measured virtual photons in heavy-ion collisions as well as in protonand ion-induced reactions in the energy range of a few GeV. Thanks to the penetrating nature of electromagnetic probes, this allows to study thermal and microscopic properties of hadronic matter in the high netbaryon density and moderate temperature region of the QCD phase diagram.
In this contribution, we focus on multi-differential spectra and collective azimuthal flow patterns of dilepton sources in Au+Au collisions at $\sqrt{s_{NN}} = 2.42$ GeV and Ag+Ag collisions at $\sqrt{s_{NN}} = 2.55$ and 2.42 GeV in comparison with hadronic probes sensitive to the freeze-out stage. It is now accompanied by the measurements in p+p reactions at $\sqrt{s_{NN}} = 2.55$ and 3.46 GeV serves as a baseline for dilepton studies in heavy-ion collisions at HADES and facilities, including FAIR.
Very soft dileptons are predicted to be sensitive to electrical conductivity of the medium and to precursor phenomena in the vicinity of the transition to color-superconducting phases. This motivated dedicated runs at HADES with magnetic fields strength reduced to 5% of the maximum value and increased acceptance for low-momentum leptons. We will discuss the essential steps towards the study of such soft dileptons.
We also give an outlook to the analysis of new HADES data at even lower beam energies that further extend excitation functions of dilepton observables
| Is this an experimental talk? | Yes |
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| Is this on behalf of a collaboration? | Yes |
| Which collaboration? | HADES |
| Are you willing to present as a poster if it is not selected for oral presentation? | Yes |