The first measurement of the dependence of $\gamma \gamma \to {\mu }^{+}{\mu }^{-}$ production on the multiplicity of neutrons emitted very close to the beam direction in ultraperipheral heavy ion collisions is reported. Data for lead-lead interactions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$, with an integrated luminosity of approximately $1.5{\mathrm{nb}}^{-1}$, are collected using the CMS detector at the LHC. The azimuthal correlations between the two muons in the invariant mass region $8<m_{\mu \mu }<60\mathrm{GeV}$ are extracted for events including 0, 1, or at least 2 neutrons detected in the forward pseudorapidity range $|\eta |>8.3$. The back-to-back correlation structure from leading-order photon-photon scattering is found to be significantly broader for events with a larger number of emitted neutrons from each nucleus, corresponding to interactions with a smaller impact parameter. This observation provides a data-driven demonstration that the average transverse momentum of photons emitted from relativistic heavy ions has an impact parameter dependence. These results provide new constraints on models of photon-induced interactions in ultraperipheral collisions. They also provide a baseline to search for possible final-state effects on lepton pairs caused by traversing a quark-gluon plasma produced in hadronic heavy ion collisions.

中文翻译：

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超外围铅铅碰撞中Dimuon非共面性的前向中子多重性相关性观察 atsNN=5.02TeV

第一次测量依赖性 $\gamma \gamma \to {\mu }^{+}{\mu }^{-}$报告了在超外围重离子碰撞中非常接近束流方向发射的中子的多样性。潜在客户互动的数据$\sqrt{{秒}_{NN}}=5.02\mathrm{伏特}$, 综合光度约为 $1.5{\mathrm{nb}}^{-1}$, 使用 LHC 上的 CMS 检测器收集。不变质量区两个μ子的方位角相关性$8<{米}_{\mu \mu }<60\mathrm{电子伏特}$ 提取事件，包括在前向伪快速范围内检测到的 0、1 或至少 2 个中子 $|\eta |>8.3$. 对于从每个原子核发射出大量中子的事件，前导光子-光子散射的背靠背相关结构明显更广泛，对应于具有较小撞击参数的相互作用。这一观察提供了一个数据驱动的证明，即从相对论重离子发射的光子的平均横向动量具有撞击参数依赖性。这些结果为超外围碰撞中的光子诱导相互作用模型提供了新的约束。它们还提供了一个基线，以搜索由穿越强子重离子碰撞中产生的夸克-胶子等离子体引起的轻子对可能的终态效应。