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arXiv 2107.09330hep-ex
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用ATLAS探测器测量13 TeV的$pp$碰撞中孤立光子对的产生截面

Measurement of the production cross section of pairs of isolated photons in $pp$ collisions at 13 TeV with the ATLAS detector

ATLAS Collaboration

摘要:

本文报道了在$\sqrt{s}=13$ TeV质子-质子碰撞中瞬时光子对产生的测量结果。这些数据由大型强子对撞机上的ATLAS探测器记录,其积分亮度为139 fb $^{-1}$。选择在探测器的良好仪器化区域中具有两个光子的事件。光子需要被隔离,并且对于领先(子领先)光子具有$p_\mathrm{T,γ_{1(2)}} > 40(30)$ GeV的横向动量。测量了双光子系统的微分截面随几个观测量的变化,并与最新的Monte Carlo和固定阶计算的理论预测进行了比较。从次到次到首阶计算和多支合并计算的QCD预测能够描述测量的积分和微分截面的不确定性,而低阶计算显示出显着的偏差,表明高阶微扰QCD修正是至关重要的这个过程。此外,部分子簇射的预测提供了一个很好的描述低横向动量制度的双光子系统。

英文摘要:

A measurement of prompt photon-pair production in proton-proton collisions at $\sqrt{s}=13$ TeV is presented. The data were recorded by the ATLAS detector at the LHC with an integrated luminosity of 139 fb$^{-1}$. Events with two photons in the well-instrumented region of the detector are selected. The photons are required to be isolated and have a transverse momentum of $p_\mathrm{T,γ_{1(2)}} > 40(30)$ GeV for the leading (sub-leading) photon. The differential cross sections as functions of several observables for the diphoton system are measured and compared with theoretical predictions from state-of-the-art Monte Carlo and fixed-order calculations. The QCD predictions from next-to-next-to-leading-order calculations and multi-leg merged calculations are able to describe the measured integrated and differential cross sections within uncertainties, whereas lower-order calculations show significant deviations, demonstrating that higher-order perturbative QCD corrections are crucial for this process. The resummed predictions with parton showers additionally provide an excellent description of the low transverse-momentum regime of the diphoton system.

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