论文标题
在$ \ sqrt {s_ \ mathrm {nn}} = $ 5.02 TEV中观察超递pb-pb碰撞中dimuon acoplanarity的正向中子多样性依赖性
Observation of forward neutron multiplicity dependence of dimuon acoplanarity in ultraperipheral Pb-Pb collisions at $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV
论文作者
论文摘要
报告了$γγ$ $ \ $ \ $μ^{+}μ^{ - } $的依赖性在超疗养重离子碰撞中非常接近光束方向发射的中子的生产。使用$ \ sqrt {s_ \ mathrm {nn}} = $ 5.02 TEV的铅铅交互的数据，使用CMS检测器在LHC上收集了大约1.5 nb $^{ - 1} $的集成发光度。在不变质量区域中的两个muons之间的方位相关性8 $ \ lt $ $ $ $ m_ {μμm_} $ $ \ lt $ 60 GEV是针对事件提取的，包括0、1，1或至少2个在正向伪造范围中检测到的中子，或至少2个中子。发现来自前阶光子光子散射的背对背相关结构对于来自每个核的发射中子较大的事件的事件明显宽，与较小的冲击参数相互作用。该观察结果提供了一个数据驱动的证明，即从相对论重离子发出的光子的平均横向动量具有影响参数的依赖性。这些结果对超遗嘱性碰撞中光子诱导相互作用的模型提供了新的限制。他们还提供了一个基线，以搜索通过穿越HADRONIC重离子碰撞中产生的夸克 - 网状等离子体引起的对Lepton对的最终影响。
The first measurement of the dependence of $γγ$ $\to$ $μ^{+}μ^{-}$ 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 $\sqrt{s_\mathrm{NN}} =$ 5.02 TeV, with an integrated luminosity of approximately 1.5 nb$^{-1}$, were collected using the CMS detector at the LHC. The azimuthal correlations between the two muons in the invariant mass region 8 $\lt$ $m_{μμ}$ $\lt$ 60 GeV are extracted for events including 0, 1, or at least 2 neutrons detected in the forward pseudorapidity range $|η|$ $\gt$ 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.
