论文标题
观察$γγ\至toτ$在Pb+Pb碰撞中的过程以及$τ$ -Lepton异常磁矩与Atlas检测器的约束
Observation of the $γγ\toττ$ process in Pb+Pb collisions and constraints on the $τ$-lepton anomalous magnetic moment with the ATLAS detector
论文作者
论文摘要
This Letter reports the observation of $τ$-lepton pair production in ultraperipheral lead-lead collisions, $\text{Pb+Pb} \to \text{Pb}(γγ\to ττ)\text{Pb}$, and constraints on the $τ$-lepton anomalous magnetic moment, $a_τ$.该数据集对应于1.44 nb $^{ - 1} $ lhc pb+pb碰撞的$ \ sqrt {s _ {s _ {_ \ text {nn}} = 5.02 $ tev tev tev $ \ sqrt {s _ {s _ {_ \ text {nn}} = 5.02 $ tev。其他$τ$ -Lepton衰减，几乎没有其他中央检测器活动的轨迹，没有前向中子。在PB+PB碰撞中观察到$γγ\至ττ$过程，其显着性超过5个标准偏差，并且信号强度为$μ_{τττ} = 1.03^{+0.06} _ { - 0.05} $，假设$ a____________。要测量$a_τ$，使用dimuon（$γγ\至μμ$）控制样品来限制系统的不确定性，对$τ$ -Lepton候选者的MUON横向momentum分布进行拟合。 $a_τ$的观察到的95％置信度间隔为$ -0.057 <a_τ<0.024 $。
This Letter reports the observation of $τ$-lepton pair production in ultraperipheral lead-lead collisions, $\text{Pb+Pb} \to \text{Pb}(γγ\to ττ)\text{Pb}$, and constraints on the $τ$-lepton anomalous magnetic moment, $a_τ$. The dataset corresponds to an integrated luminosity of 1.44 nb$^{-1}$ of LHC Pb+Pb collisions at $\sqrt{s_{_\text{NN}}} = 5.02$ TeV recorded by the ATLAS experiment in 2018. Selected events contain one muon from a $τ$-lepton decay, an electron or charged-particle track(s) from the other $τ$-lepton decay, little additional central-detector activity, and no forward neutrons. The $γγ\to ττ$ process is observed in Pb+Pb collisions with a significance exceeding 5 standard deviations, and a signal strength of $μ_{ττ} = 1.03^{+0.06}_{-0.05}$ assuming the Standard Model value for $a_τ$. To measure $a_τ$, a template fit to the muon transverse-momentum distribution from $τ$-lepton candidates is performed, using a dimuon ($γγ\to μμ$) control sample to constrain systematic uncertainties. The observed 95% confidence-level interval for $a_τ$ is $-0.057 < a_τ< 0.024$.
