Impact of the Coulomb field on charged-pion spectra in few-GeV heavy-ion collisions

0560994 - ÚJF 2023 RIV US eng J - Journal Article
Adamczewski-Musch, J. - Arnold, O. - Behnke, C. - Belounnas, A. - Chlad, Lukáš - Kugler, Andrej - Rodriguez Ramos, Pablo - Sobolev, Yuri, G. - Svoboda, Ondřej - Tlustý, Pavel - Wagner, Vladimír … Total 127 authors
Impact of the Coulomb field on charged-pion spectra in few-GeV heavy-ion collisions.
European Physical Journal A. Roč. 58, č. 9 (2022), č. článku 166. ISSN 1434-6001. E-ISSN 1434-601X
R&D Projects: GA MŠMT LTT17003; GA MŠMT EF18_046/0016066
Research Infrastructure: FAIR-CZ II - 90112
Institutional support: RVO:61389005
Keywords : Coloumb field * heavy ion collisions * HBT source
OECD category: Particles and field physics
Impact factor: 2.6, year: 2022
Method of publishing: Open access
https://doi.org/10.1140/epja/s10050-022-00796-6

In nuclear collisions the incident protons generate a Coulomb field which acts on produced charged particles. The impact of these interactions on charged-pion transverse-mass and rapidity spectra, as well as on pion-pion momentum correlations is investigated in Au + Au collisions at root s(NN) = 2.4 GeV. We show that the low-m t region (m(t) < 0.2 GeV/c(2)) can be well described with a Coulomb-modified Boltzmann distribution that also takes changes of the Coulomb field during the expansion of the fireball into account. The observed centrality dependence of the fitted mean Coulomb potential energy deviates strongly from a A(part)(2/3) scaling, indicating that, next to the fireball, the non-interacting charged spectators have to be taken into account. For the most central collisions, the Coulomb modifications of the HBT source radii are found to be consistent with the potential extracted from the single-pion transverse-mass distributions. This finding suggests that the region of homogeneity obtained from two-pion correlations coincides with the region in which the pions freeze-out. Using the inferred mean-square radius of the charge distribution at freeze-out, we have deduced a baryon density, in fair agreement with values obtained from statistical hadronization model fits to the particle yields.
Permanent Link: https://hdl.handle.net/11104/0333752