Probing dense baryon-rich matter with virtual photons

0509905 - ÚJF 2020 RIV GB eng J - Journal Article
Adamczewski-Musch, J. - Arnold, O. - Behnke, C. - Belounnas, A. - Belyaev, A. - Chlad, Lukáš - Kugler, Andrej - Rodriguez Ramos, Pablo - Sobolev, Yuri, G. - Svoboda, Ondřej - Tlustý, Pavel - Wagner, Vladimír … Total 116 authors
Probing dense baryon-rich matter with virtual photons.
Nature Physics. Roč. 15, č. 10 (2019), s. 1040-1047. ISSN 1745-2473. E-ISSN 1745-2481
R&D Projects: GA ČR GA13-06759S; GA MŠMT LM2015049; GA MŠMT LTT17003; GA MŠMT EF16_013/0001677
Institutional support: RVO:61389005
Keywords : HADES * collisions * QCD matter
OECD category: Nuclear physics
Impact factor: 19.256, year: 2019
Method of publishing: Limited access
https://doi.org/10.1038/s41567-019-0583-8

About 10 mu s after the Big Bang, the universe was filled-in addition to photons and leptons-with strong-interaction matter consisting of quarks and gluons, which transitioned to hadrons at temperatures close to kT = 150 MeV and densities several times higher than those found in nuclei. This quantum chromodynamics (QCD) matter can be created in the laboratory as a transient state by colliding heavy ions at relativistic energies. The different phases in which QCD matter may exist depend for example on temperature, pressure or baryochemical potential, and can be probed by studying the emission of electromagnetic radiation. Electron-positron pairs emerge from the decay of virtual photons, which immediately decouple from the strong interaction, and thus provide information about the properties of QCD matter at various stages. Here, we report the observation of virtual photon emission from baryon-rich QCD matter. The spectral distribution of the electron-positron pairs is nearly exponential, providing evidence for a source of temperature in excess of 70 MeV with constituents whose properties have been modified, thus reflecting peculiarities of strong-interaction QCD matter. Its bulk properties are similar to the dense matter formed in the final state of a neutron star merger, as apparent from recent multimessenger observation.
Permanent Link: http://hdl.handle.net/11104/0300494