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arXiv 2202.12134hep-ex
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用$\sqrt{s}=13$ ATLAS探测器测量高横动量顶夸克对事件的微分截面和对超出标准模型贡献的限制

Measurements of differential cross-sections in top-quark pair events with a high transverse momentum top quark and limits on beyond the Standard Model contributions to top-quark pair production with the ATLAS detector at $\sqrt{s}=13$ TeV

ATLAS Collaboration

摘要:

利用ATLAS实验在LHC质子-质子碰撞过程中收集的139 fb $^{-1}$数据,给出了强子衰变顶夸克的横动量大于$355$ GeV,另一个顶夸克衰变为$\ell νb$的顶夸克对产生截面的测量结果.在$\sqrt{s}=13$ TeV的基准截面被测量为$σ= 1.267 \pm 0.005 \pm 0.053$ pb,其中的不确定性反映了有限数量的数据事件和系统的不确定性,给出了$4.2\%$的总不确定性。作为表征$t\bar{t}$系统和事件中的附加辐射的变量的函数,差分测量横截面。结果进行了比较与各种蒙特卡罗发电机,包括比较发电机重新加权,以匹配在下一个到下一个到领先的顺序的部分子级计算。重新加权提高了数据和理论之间的一致性。利用测量的顶夸克横动量分布,在有效场论框架下对六维算符$O_{tG}$和$O_{tq}^{(8)}$的Wilson系数进行了限制.

英文摘要:

Cross-section measurements of top-quark pair production where the hadronically decaying top quark has transverse momentum greater than $355$ GeV and the other top quark decays into $\ell νb$ are presented using 139 fb$^{-1}$ of data collected by the ATLAS experiment during proton-proton collisions at the LHC. The fiducial cross-section at $\sqrt{s}=13$ TeV is measured to be $σ= 1.267 \pm 0.005 \pm 0.053$ pb, where the uncertainties reflect the limited number of data events and the systematic uncertainties, giving a total uncertainty of $4.2\%$. The cross-section is measured differentially as a function of variables characterising the $t\bar{t}$ system and additional radiation in the events. The results are compared with various Monte Carlo generators, including comparisons where the generators are reweighted to match a parton-level calculation at next-to-next-to-leading order. The reweighting improves the agreement between data and theory. The measured distribution of the top-quark transverse momentum is used to set limits on the Wilson coefficients of the dimension-six operators $O_{tG}$ and $O_{tq}^{(8)}$ in the effective field theory framework.

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