论文标题
通过$γγ$散射在$ \ sqrt {s _ {_ \ mathrm {nn}}} = 5.02 $ tev的$ \ sqrt {
Measurement of muon pairs produced via $γγ$ scattering in non-ultraperipheral Pb+Pb collisions at $\sqrt{s_{_\mathrm{NN}}} = 5.02$ TeV with the ATLAS detector
论文作者
论文摘要
在$ \ sqrt {s _ {_ \ mathrm {nn}}} = 5.02 $ tev中，在$ \ sqrt {s _ {s _ {s _ {s _ {_ \ sqrt {s _ \ sqrt {s _ {s _ {s _ {s _ {s _ {该测量使用LHC的2015年和2018 PB+PB数据研究期的ATLAS数据，其集成发光度为$ 1.94〜 \ MATHRM {NB}^{ - 1} $。 $γγ\rightArrowμ^+μ^ - $对通过对成对动量不对称和丙型球的选择来识别。 Dimuon产生的差分横截面以不同的中心性，平均哑光动量和配对速度间隔作为链球界的函数和$ k_ \ perp $，这是一种哑球相对于另一个muon的横向动量踢。还可以进行测量，这是MUON的速度分离的函数以及MUON对相对于二阶事件平面的角度，以测试Quark-Gluon等离子体中产生的磁场是否影响所测得的MUON。证实了对中心性分布的中心性依赖性拓宽的事先观察。此外，测量的提高精度揭示了具有较小的链球界面的对数或$ k _ {\ perp} $值的耗尽。观察到给定的中心点间隔中的丙型平移分布与均值的均值$ p _ {\ mathrm {t}} $变化，但是$ k _ {\ perp} $ distributions却没有。与最近的理论预测进行了比较。未观察到与磁场对Dimuons的影响相关的预测趋势。
Results of a measurement of dimuon photoproduction in non-ultraperipheral Pb+Pb collisions at $\sqrt{s_{_\mathrm{NN}}} = 5.02$ TeV are presented. The measurement uses ATLAS data from the 2015 and 2018 Pb+Pb data-taking periods at the LHC with an integrated luminosity of $1.94~\mathrm{nb}^{-1}$. The $γγ\rightarrow μ^+μ^-$ pairs are identified via selections on pair momentum asymmetry and acoplanarity. Differential cross-sections for dimuon production are measured in different centrality, average muon momentum and pair rapidity intervals as functions of acoplanarity and $k_\perp$, the transverse momentum kick of one muon relative to the other. Measurements are also made as a function of the rapidity separation of the muons and the angle of the muon pair relative to the second-order event plane to test whether magnetic fields generated in the quark-gluon plasma affect the measured muons. A prior observation of a centrality-dependent broadening of the acoplanarity distribution is confirmed. Furthermore, the improved precision of the measurement reveals a depletion in the number of pairs having small acoplanarity or $k_{\perp}$ values in more central collisions. The acoplanarity distributions in a given centrality interval are observed to vary with the mean-$p_{\mathrm{T}}$ of the muons in the pair, but the $k_{\perp}$ distributions do not. Comparisons with recent theoretical predictions are made. The predicted trends associated with effects of magnetic fields on the dimuons are not observed.
