We present high-statistic data on charged-pion emission from Au + Au collisions at \(\sqrt{s_{\mathrm{NN}}} = 2.4~\hbox {GeV}\) (corresponding to \(E_{beam} = 1.23~\hbox {A GeV}\)) 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 \(2.5~\sigma \) 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.

我们提供有关\（\ sqrt {s _ {\ mathrm {NN}}} = 2.4〜\ hbox {GeV} \）处Au + Au碰撞产生的带电离子排放的高统计数据（对应于\（E_ {beam} = 1.23〜\ hbox {A GeV} \）），在四个中心类中，占最主要碰撞的0–40％。将数据作为横向动量，横向质量，速度和极角的函数进行分析。每个参与核子的介子数随中心度的增加而适度降低。发现即使对于最中心的事件类别，极角分布也是非各向同性的。我们在pion多重性上的结果与可用的世界数据的总体趋势非常吻合，但低于\（2.5〜\ sigma \）FOPI实验获得的数据是在稍低的光束能量下测得的。我们将数据与最先进的运输模型计算（PHSD，IQMD，PHQMD，GiBUU和SMASH）进行比较，发现测量结果与这些计算结果之间存在实质性差异。