论文标题
在$ \ sqrt {s _ {_ \ text {nn}}} = 5.02 $ tev with atlas中
Exclusive dielectron production in ultraperipheral Pb+Pb collisions at $\sqrt{s_{_\text{NN}}} = 5.02$ TeV with ATLAS
论文作者
论文摘要
使用$ \ Mathcal {l} _ \ Mathrm {int} = 1.72 \;来自铅核从$ \ sqrt {s _ {_ {_ {\ text {nn}}} = 5.02 $ tev记录的ATLAS检测器在LHC记录的数据，从$ \ sqrt {s _ {_ {_ {_ {_ {_ {s _ {s _ {s _ {s _ {s _ {s _ {s _ {s _ {s _ {s _ {s _ {s _ {感兴趣的过程通过相对论铅核的强电磁场中的光子 - 光子相互作用进行。在由以下要求定义的基准区域中测量了二元发电的生产：电子横向动量，$ p _ {\ textrm {t}}}}^{e}> 2.5 $ GEV，absolute electron pseudorapidity，$ | | e |η^{e} | <2.5 $，Dielectron系统的不变质量，$ m_ {ee}> 5 $ GEV和DIELECTON对的横向动量，$ p _ {\ textrm {t}}}^{ee} {ee} <2 $ gev。差分横截面的测量是$ m_ {ee} $的函数，平均$ p _ {\ textrm {\ textrm {t}}}^{e} $，Dielectron System的绝对快速性，$ | y_ {ee} | $，以及在dieLectRectres frime the dieLectRectrim frive the Intive the CosInemement and in CosInemement and Inception the Inter Interiment and Inter-cos \ | $ | 方向。总体集成基准横截面的测量为$ 215 \ pm 1 \ text {（stat。）} ^{+23} _ { - 20} \ text {（syst。）} \ pm 4 \ pm 4 \ text {（lumi。）}} \; μ$ b。在实验不确定性中，测得的综合横截面与蒙特卡洛计划星光和超奇的QED预测非常吻合，这证实了初始光子通量的广泛特征。差分横截面显示了这些预测的系统差异，这些预测更为明显，在高$ | y_ {ee} | $和$ | \cosθ^*| $ values。
Exclusive production of dielectron pairs, $γγ\rightarrow e^+e^-$, is studied using $\mathcal{L}_\mathrm{int}=1.72\; \mathrm{nb^{-1}}$ of data from ultraperipheral collisions of lead nuclei at $\sqrt{s_{_{\text{NN}}}} = 5.02$ TeV recorded by the ATLAS detector at the LHC. The process of interest proceeds via photon-photon interaction in the strong electromagnetic fields of relativistic lead nuclei. Dielectron production is measured in the fiducial region defined by following requirements: electron transverse momentum, $p_{\textrm{T}}^{e} > 2.5$ GeV, absolute electron pseudorapidity, $|η^{e}| < 2.5$, invariant mass of the dielectron system, $m_{ee} > 5$ GeV, and transverse momentum of the dielecton pair, $p_{\textrm{T}}^{ee} < 2$ GeV. Differential cross-sections are measured as a function of $m_{ee}$, average $p_{\textrm{T}}^{e}$, absolute rapidity of the dielectron system, $|y_{ee}|$, and scattering angle in the dielectron rest frame, $|\cosθ^*|$ in the inclusive sample, and also under the requirement of no activity in the forward direction. The total integrated fiducial cross-section is measured to be $215 \pm 1 \text{(stat.)} ^{+23}_{-20} \text{(syst.)} \pm 4 \text{(lumi.)}\; μ$b. Within experimental uncertainties the measured integrated cross-section is in good agreement with the QED predictions from the Monte Carlo programs Starlight and SuperChic, confirming the broad features of the initial photon fluxes. The differential cross-sections show systematic differences with these predictions which are more pronounced at high $|y_{ee}|$ and $|\cosθ^*|$ values.
