Charged-pion production in Au+ Au collisions at √sNN=2.4GeV : HADES Collaboration

Adamczewski-Musch, J.; Arnold, O.; Behnke, C.; Belounnas, A.; Belyaev, A.; Berger-Chen, J. C.; Blanco, A.; Blume, C.; Bohmer, M.; Bordalo, P.; Chernenko, S.; Chlad, L.; Ciepal, I.; Deveaux, C.; Dreyer, J.; Epple, E.; Fabbietti, L.; Fateev, O.; Filip, P.; Fonte, P.; Franco, C.; Friese, J.; Frohlich, I.; Galatyuk, T.; Garzon, J. A.; Gernhauser, R.; Glassel, S.; Golubeva, M.; Greifenhagen, R.; Guber, F.; Gumberidze, M.; Harabasz, S.; Heinz, T.; Hennino, T.; Hlavac, S.; Hohne, C.; Holzmann, R.; Ierusalimov, A.; Ivashkin, A.; Kampfer, B.; Karavicheva, T.; Kardan, B.; Koenig, I.; Koenig, W.; Kohls, M.; Kolb, B. W.; Korcyl, G.; Kornakov, G.; Kornas, F.; Kotte, R.; Kugler, A.; Kunz, T.; Kurepin, A.; Kurilkin, A.; Kurilkin, P.; Ladygin, V.; Lalik, R.; Lapidus, K.; Lebedev, A.; Lopes, L.; Lorenz, M.; Mahmoud, T.; Maier, L.; Malige, A.; Mangiarotti, A.; Markert, J.; Matulewicz, T.; Maurus, S.; Metag, V.; Michel, J.; Mihaylov, D. M.; Morozov, S.; Muntz, C.; Munzer, R.; Naumann, L.; Nowakowski, K.; Parpottas, Y.; Pechenov, V.; Pechenova, O.; Petukhov, O.; Piasecki, K.; Pietraszko, J.; Przygoda, W.; Pysz, K.; Ramos, S.; Ramstein, B.; Rathod, N.; Reshetin, A.; Rodriguez-Ramos, P.; Rosier, P.; Rost, A.; Rustamov, A.; Sadovsky, A.; Salabura, P.; Scheib, T.; Schuldes, H.; Schwab, E.; Scozzi, F.; Seck, F.; Sellheim, P.; Selyuzhenkov, I.; Siebenson, J.; Silva, L.; Singh, U.; Smyrski, J.; Sobolev, Y. G.; Spataro, S.; Spies, S.; Strobele, H.; Stroth, J.; Sturm, C.; Svoboda, O.; Szala, M.; Tlusty, P.; Traxler, M.; Tsertos, H.; Usenko, E.; Wagner, V.; Wendisch, C.; Wiebusch, M. G.; Wirth, J.; Wojcik, D.; Zanevsky, Y.; Zumbruch, P.

doi:10.1140/epja/s10050-020-00237-2

We present high-statistic data on charged-pion emission from Au + Au collisions at sNN=2.4GeV (corresponding to Ebeam=1.23A 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 2.5σ 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.