arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2007.14040hep-ex
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用ATLAS探测器检验$t\bar{t}$事件的PDMATHAAC-玻色子衰变中$τ$和$μ$轻子耦合的普适性

Test of the universality of $τ$ and $μ$ lepton couplings in $W$-boson decays from $t\bar{t}$ events with the ATLAS detector

ATLAS Collaboration

摘要:

粒子物理学的标准模型包含了我们目前在最小尺度上对物理学的最佳理解。这个理论的一个基本公理是不同代轻子与电弱规范玻色子耦合的普适性。测量$W$玻色子与$τ$ -轻子和μ子的衰变率之比,即$R(τ/μ) = B(W \to τν_τ)/B(W \to μν_μ)$,是对这一公理的一个重要检验。基于ATLAS探测器在$\sqrt{s}=13$ TeV质子-质子碰撞中记录的139 fb ${}^{-1}$数据,提出了一种利用双轻子$t\bar{t}$事件的新技术来测量这个量。从$W$玻色子和那些从中间$τ$轻子起源的μ子区分使用$τ$轻子的寿命,通过μ子横向碰撞参数,和μ子横向动量谱的差异。$R(τ/μ)$的值为$0.992 \pm 0.013 [\pm 0.007 (stat) \pm 0.011 (syst)]$,与标准模型中的普适轻子耦合假设一致。这是迄今为止对这个比率最精确的测量,也是大型强子对撞机唯一的测量。

英文摘要:

The Standard Model of particle physics encapsulates our current best understanding of physics at the smallest scales. A fundamental axiom of this theory is the universality of the couplings of the different generations of leptons to the electroweak gauge bosons. The measurement of the ratio of the rate of decay of $W$ bosons to $τ$-leptons and muons, $R(τ/μ) = B(W \to τν_τ)/B(W \to μν_μ)$, constitutes an important test of this axiom. A measurement of this quantity with a novel technique using di-leptonic $t\bar{t}$ events is presented based on 139 fb${}^{-1}$ of data recorded with the ATLAS detector in proton--proton collisions at $\sqrt{s}=13$ TeV. Muons originating from $W$ bosons and those originating from an intermediate $τ$-lepton are distinguished using the lifetime of the $τ$-lepton, through the muon transverse impact parameter, and differences in the muon transverse momentum spectra. The value of $R(τ/μ)$ is found to be $0.992 \pm 0.013 [\pm 0.007 (stat) \pm 0.011 (syst)]$ and is in agreement with the hypothesis of universal lepton couplings as postulated in the Standard Model. This is the most precise measurement of this ratio, and the only such measurement from the Large Hadron Collider, to date.

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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