利用ATLAS探测器在质心系能量√s=13TeV的质子-质子碰撞中，对矢量类T夸克对产生并衰变为顶夸克与自旋-0粒子且最终态为双光子的过程进行搜索
Search for pair-production of vector-like $T$ quarks decaying into a top quark and a spin-0 particle in the diphoton final state in proton proton collisions at $\sqrt{s}=13$ TeV with the ATLAS detector
AI总结：
ATLAS探测器利用140 fb⁻¹的13TeV质子-质子碰撞数据，首次搜索矢量类T夸克对衰变为顶夸克与自旋-0粒子且最终态为双光子的过程，未发现超出标准模型本底的显著超出量，给出了fiducial截面乘分支比的上限。
AI中文摘要：
本文对矢量类T夸克（VLQ）的对产生过程开展搜索，假设每个VLQ衰变产生1个顶夸克和1个超出标准模型的（赝）标量粒子S。该搜索针对的事件需满足：至少存在1个共振态S→γγ衰变，且来自其他末态粒子的总横动量与缺失横动量较大。分析采用的是ATLAS探测器在2015年至2018年期间记录的质心系能量√s=13TeV的质子-质子碰撞数据，对应积分亮度为140 fb⁻¹。这是首次针对该末态开展的VLQ搜索，未观测到超出标准模型本底的显著超出量。该分析在很大程度上是模型无关的，但针对的是衰变为包含电弱玻色子或t$\bar{t}$的末态的级联衰变，结果以 fiducial 截面乘以分支比的上限形式呈现，作为VLQ与自旋-0粒子质量的函数，其中fiducial体积由自旋-0粒子衰变产生的光子的运动学要求定义。
英文摘要：
A search for pair-produced vector-like T quarks (VLQs) is presented. Each VLQ is assumed to decay into a top quark and an exotic (pseudo)scalar S. The search targets events with at least one resonant $S \to γγ$ decay and large summed transverse momentum and missing transverse momentum from other final-state particles. The analysis uses data from $pp$ collisions at a centre-of-mass energy of $\sqrt{s}$ = 13 TeV recorded by the ATLAS detector from 2015 to 2018 and corresponding to an integrated luminosity of 140 fb$^{-1}$. This is the first VLQ search performed in this final state. No significant excess over the Standard Model background is observed. The analysis is model-independent to a large extent but targets cascade decays into final states with electroweak bosons or $t\bar{t}$. Results are provided in the form of upper limits on the fiducial cross-section times branching ratio as a function of the masses of the VLQ and the spin-0 particle. The fiducial volume is defined by kinematic requirements on the photons from the spin-0 decay.
