Publication Date:
2020-10-01
Description:
We present high-statistic data on charged-pion emission from Au + Au collisions at $$sqrt{s_{mathrm{NN}}} = 2.4~hbox {GeV}$$ s NN = 2.4 GeV (corresponding to $$E_{beam} = 1.23~hbox {A GeV}$$ E beam = 1.23 A GeV ) in four centrality classes in the range 0–40% of the most central collisions. The data are analyzed as a function of transverse momentum, transverse mass, rapidity, and polar angle. Pion multiplicity per participating nucleon decreases moderately with increasing centrality. The polar angular distributions are found to be non-isotropic even for the most central event class. Our results on pion multiplicity fit well into the general trend of the available world data, but undershoot by $$2.5~sigma $$ 2.5 σ data from the FOPI experiment measured at slightly lower beam energy. We compare our data to state-of-the-art transport model calculations (PHSD, IQMD, PHQMD, GiBUU and SMASH) and find substantial differences between the measurement and the results of these calculations.
Print ISSN:
1434-6001
Electronic ISSN:
1434-601X
Topics:
Physics
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