Ajaz Muhammad, Haj Ismail Abd Al Karim, Waqas Muhammad, Suleymanov Mais, AbdelKader Atef, Suleymanov Rustam
Department of physics, Abdul Wali Khan University Mardan, Mardan, 23200, Pakistan.
College of Humanities and Sciences, Ajman University, Ajman, 346, United Arab Emirates.
Sci Rep. 2022 May 17;12(1):8142. doi: 10.1038/s41598-022-11685-9.
The measured charged particle [Formula: see text] spectra in proton-proton collisions obtained by the CMS experiment at CERN is compared with the simulation results of EPOS-LHC and Pythia8.24 models at 7 TeV center-of-mass energy. The Pythia8.24 model describes the experimental data very well, particularly in the high [Formula: see text] region. The model also predicts the [Formula: see text] spectra for [Formula: see text] [Formula: see text] [Formula: see text] < 2.4 at 0 [Formula: see text] [Formula: see text] [Formula: see text] 6 [Formula: see text]. The EPOS-LHC model underpredicts the [Formula: see text] spectra from 0.1 to 2 [Formula: see text] in all [Formula: see text] bins for about 20% and the [Formula: see text] spectrum from 0.1 to 4.2 [Formula: see text] for [Formula: see text] [Formula: see text] [Formula: see text] < 2.4 by about 15% while reasonably predicts well for [Formula: see text] > 4.2 [Formula: see text] within the experimental errors. Furthermore, to get information about collective properties of the hadronic matter, modified Hagedorn function with embedded transverse flow velocity and thermodynamically consistent Tsallis distribution functions are used to fit the experimental data and simulated results. The values of [Formula: see text] show that the functions fit the data and simulation results well. The parameter extracted by the functions: [Formula: see text], [Formula: see text], and [Formula: see text] decreases with increasing [Formula: see text]. The decrease in [Formula: see text] with increasing [Formula: see text] is due to the large energy deposition in lower rapidity bins producing rapid expansion due to large pressure gradient resulting quick expansion of the fireball. Similarly, large energy transfer in the lower pseudo-rapidity bin results in higher degree of excitation of the system which results larger values of [Formula: see text] and [Formula: see text]. The values of the fit constant [Formula: see text] increase with [Formula: see text] where the values of [Formula: see text] extracted from Pythia8.24 are closer to the data than the EPOS-LHC model. The Pythia8.24 model has better prediction than the EPOS-LHC model which might be connected to its flow-like features and color re-connections resulting from different Parton interactions in the initial and final state.
将欧洲核子研究组织（CERN）的紧凑缪子线圈（CMS）实验在质子-质子碰撞中测得的带电粒子[公式：见原文]谱，与EPOS-LHC和Pythia8.24模型在质心能量为7 TeV时的模拟结果进行了比较。Pythia8.24模型能很好地描述实验数据，尤其是在高[公式：见原文]区域。该模型还预测了在0[公式：见原文][公式：见原文][公式：见原文]6[公式：见原文]时，[公式：见原文][公式：见原文][公式：见原文]<2.4的[公式：见原文]谱。EPOS-LHC模型在所有[公式：见原文]区间内，对0.1至2[公式：见原文]的[公式：见原文]谱预测低约20%，对[公式：见原文][公式：见原文][公式：见原文]<2.4时0.1至4.2[公式：见原文]的[公式：见原文]谱预测低约15%，而在实验误差范围内，对于[公式：见原文]>4.2[公式：见原文]的情况预测较好。此外，为了获取有关强子物质集体性质的信息，使用了嵌入横向流速度的修正哈格多恩函数和热力学上一致的Tsallis分布函数来拟合实验数据和模拟结果。[公式：见原文]的值表明这些函数能很好地拟合数据和模拟结果。由这些函数提取的参数：[公式：见原文]、[公式：见原文]和[公式：见原文]随[公式：见原文]的增加而减小。[公式：见原文]随[公式：见原文]增加而减小是由于在较低快度区间有大量能量沉积，由于大的压力梯度导致火球快速膨胀。类似地，在较低赝快度区间的大量能量转移导致系统的激发程度更高，从而导致[公式：见原文]和[公式：见原文]的值更大。拟合常数[公式：见原文]的值随[公式：见原文]增加，其中从Pythia8.24提取的[公式：见原文]值比EPOS-LHC模型更接近数据。Pythia8.24模型比EPOS-LHC模型有更好的预测，这可能与其类流特征以及初始和末态中不同部分子相互作用导致的颜色重连有关。
