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arXiv 2008.02036nucl-ex
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在LHC精密物理时代重离子与ALICE碰撞中轻中性介子的产生

Light neutral meson production in heavy ion collisions with ALICE in the era of precision physics at the LHC

Mike Sas

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arXiv admin note: text overlap with arXiv:2008.02039
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摘要：

AA碰撞中轻中性介子的产生是对LHC中重离子碰撞中夸克-胶子等离子体（QGP）物理的探索。更具体地说，在AA碰撞的中心依赖中性介子光谱相比，其光谱在最小偏置PP碰撞，硬碰撞的数量缩放，提供信息的部分子穿越QGP的能量损失。测量允许以高精度测试理论模型计算的预测。此外，$π^{0}$和$η$介子的衰变是所有直接光子测量的主要背景。因此，突破中性介子产生的精确度是了解QGP温度和时空演化的关键。在ALICE实验中，中性介子可以通过衰变为两个光子来检测。后者可以使用两个量热计EMCal和PHOS或通过检测器材料中的转换来重建。由于转换光子的动量分辨率低至很低的$p_{\mathrm{T}}$，而量热计在高$p_{\mathrm{T}}$时具有很高的重构效率和触发能力，使得我们能够在很宽的运动学范围内测量轻中性介子的与$p_{\mathrm{T}}$相关的不变量产额.将最先进的重建技术与LHC在运行2中提供的高统计数据相结合，使我们有机会提高测量的精度。在这些程序中，新的ALICE运行2中性介子生产的PP和铅铅碰撞在LHC能量的初步结果。

英文摘要：

The production of light neutral mesons in AA collisions probes the physics of the Quark-Gluon Plasma (QGP), which is formed in heavy-ion collisions at the LHC. More specifically, the centrality dependent neutral meson spectra in AA collisions compared to its spectra in minimum-bias pp collisions, scaled with the number of hard collisions, provides information on the energy loss of partons traversing the QGP. The measurement allows to test with high precision the predictions of theoretical model calculations. In addition, the decay of the $π^{0}$ and $η$ mesons are the dominant backgrounds for all direct photon measurements. Therefore, pushing the limits of the precision of neutral meson production is key to learning about the temperature and space-time evolution of the QGP. In the ALICE experiment neutral mesons can be detected via their decay into two photons. The latter can be reconstructed using the two calorimeters EMCal and PHOS or via conversions in the detector material. The excellent momentum resolution of the conversion photons down to very low $p_{\mathrm{T}}$ and the high reconstruction efficiency and triggering capability of calorimeters at high $p_{\mathrm{T}}$, allow us to measure the $p_{\mathrm{T}}$ dependent invariant yield of light neutral mesons over a wide kinematic range. Combining state-of-the-art reconstruction techniques with the high statistics delivered by the LHC in Run 2 gives us the opportunity to enhance the precision of our measurements. In these proceedings, new ALICE run 2 preliminary results for neutral meson production in pp and Pb--Pb collisions at LHC energies are presented.

机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。

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