Multi-differential pattern of low-mass e(+)e(-) excess from root S-NN=2.4 GeV Au+Au collisions with HADES

0502295 - ÚJF 2020 RIV NL eng J - Journal Article
Harabasz, S. - Adamczewski-Musch, J. - Arnold, O. - Arnoldi-Meadows, B. - Belounnas, A. - Chlad, Lukáš - Chudoba, Petr - Kugler, Andrej - Kushpil, Vasilij - Mikhaylov, Vasily - Prozorov, Alexandr P. - Rodriguez Ramos, Pablo - Svoboda, Ondřej - Tlustý, Pavel - Wagner, Vladimír … Total 127 authors
Multi-differential pattern of low-mass e(+)e(-) excess from root S-NN=2.4 GeV Au+Au collisions with HADES.
Nuclear Physics. A. Roč. 982, č. 2 (2019), s. 771-774. ISSN 0375-9474. E-ISSN 1873-1554.
[27th International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2018). Venice, 13.05.2018-19.05.2018]
R&D Projects: GA MŠMT LM2015049; GA MŠMT EF16_013/0001677
Institutional support: RVO:61389005
Keywords : HADES * dielectrons * azimuthal anisotropy
OECD category: Nuclear physics
Impact factor: 1.695, year: 2019
Method of publishing: Open access
https://doi.org/10.1016/j.nuclphysa.2018.09.052

The matter formed in central heavy-ion collisions at a few GeV per nucleon is commonly understood as resonance matter, a gas of nucleons and excited baryon states with a substantial contribution from mesonic, mostly pionic excitations. Yet, in the initial phase of the reaction the system is compressed to beyond nuclear ground state density and hence substantial modifications of the hadron properties are expected to occur. The spectral distribution of virtual photons measured in Au+Au collisions at 2.4 GeV center of mass energy indicates strong medium effects beyond pure superposition of individual NN collisions. We present multi-differential distributions of low-mass electron pairs. This radiation is remarkably well described assuming emission from a thermalized system. To gain deeper understanding of the microscopic origin of the radiation, we extracted the centrality dependent true (not blue-shifted) temperature, its azimuthal distribution, as well as mass-dependent effective slope parameter. Virtual photon spectra are confronted with available model calculations.
Permanent Link: http://hdl.handle.net/11104/0294245