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arXiv 2209.14903hep-ex
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利用ATLAS实验在$\sqrt{s} = 13$ TeV下通过双轻子事件测量顶夸克衰变产生的$W$玻色子的极化

Measurement of the polarisation of $W$ bosons produced in top-quark decays using dilepton events at $\sqrt{s} = 13$ TeV with the ATLAS experiment

ATLAS Collaboration

AI总结:

利用ATLAS探测器在13 TeV质子-质子碰撞数据中,通过双轻子事件测量顶夸克衰变产生的W玻色子极化,结果与标准模型预言一致。

摘要:

本文提出了一项顶夸克衰变产生的$W$玻色子极化测量,所使用的质子-质子碰撞数据质心系能量为$\sqrt{s} = 13$ TeV。这些数据由大型强子对撞机上的ATLAS探测器采集,对应的积分亮度为139 fb$^{-1}$。本次测量选取衰变末态包含两个带电轻子(电子或缪子)以及至少两个$b$标记喷注的$t\bar{t}$事件开展。极化程度从$\cos{θ^{*}}$变量的微分截面分布中提取,其中$θ^{*}$是$W$玻色子衰变产生的带电轻子动量方向,与顶夸克衰变产生的$b$夸克的反冲动量方向之间的夹角,二者均在$W$玻色子静止系中计算。针对$\cos{θ^{*}}$角,本文给出了经探测器接收度和分辨率修正的部分子水平结果。测得的纵向、左手及右手极化态占比分别为$f_{0} = 0.684 \pm 0.005\,\mathrm{(stat.)} \pm 0.014\,\mathrm{(syst.)}$、$f_{\mathrm{L}} = 0.318 \pm 0.003\,\mathrm{(stat.)} \pm 0.008\,\mathrm{(syst.)}$和$f_{\mathrm{R}} = -0.002 \pm 0.002\,\mathrm{(stat.)} \pm 0.014\,\mathrm{(syst.)}$,与标准模型预言一致。

英文摘要:

A measurement of the polarisation of $W$ bosons produced in top-quark decays is presented, using proton-proton collision data at a centre-of-mass energy of $\sqrt{s} = 13$ TeV. The data were collected by the ATLAS detector at the Large Hadron Collider and correspond to an integrated luminosity of 139 fb$^{-1}$. The measurement is performed selecting $t\bar{t}$ events decaying into final states with two charged leptons (electrons or muons) and at least two $b$-tagged jets. The polarisation is extracted from the differential cross-section distribution of the $\cos{θ^{*}}$ variable, where $θ^{*}$ is the angle between the momentum direction of the charged lepton from the $W$ boson decay and the reversed momentum direction of the $b$-quark from the top-quark decay, both calculated in the $W$ boson rest frame. Parton-level results, corrected for the detector acceptance and resolution, are presented for the $\cos{θ^{*}}$ angle. The measured fractions of longitudinal, left- and right-handed polarisation states are found to be $f_{0} = 0.684 \pm 0.005\,\mathrm{(stat.)} \pm 0.014\,\mathrm{(syst.)}$, $f_{\mathrm{L}} = 0.318 \pm 0.003\,\mathrm{(stat.)} \pm 0.008\,\mathrm{(syst.)}$ and $f_{\mathrm{R}} = -0.002 \pm 0.002\,\mathrm{(stat.)} \pm 0.014\,\mathrm{(syst.)}$, in agreement with the Standard Model prediction.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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