AI 中文总结
利用ATLAS探测器在√s=13 TeV质子-质子碰撞数据中，寻找与顶夸克对伴随产生的洛伦兹增强双τ共振态，未发现超出标准模型的显著偏差，给出了可见截面及双希格斯二重态模型信号的相关上限限制。
AI 中文摘要
本文对质量范围在20 GeV至85 GeV之间、与顶夸克-反顶夸克对伴随产生且衰变为τ轻子对的洛伦兹增强赝标量共振态a开展了寻找研究，两个τ轻子均在强子衰变模式下被重建。共振态a的增强产生使其衰变产物的角间隔很小，需采用专用的增强双τ对象，其采用定制的重建、能量刻度和鉴别流程。该分析使用大型强子对撞机上ATLAS探测器收集的质心系能量√s=13 TeV的质子-质子碰撞数据，对应积分亮度为140 fb⁻¹。未观测到超出标准模型预期背景的显著偏差，在95%置信水平下对可见截面上限设为0.19 fb。针对双希格斯二重态模型信号情景，还得到了σ(t$\bar{t}$a)×BR(a→ττ)的限制，范围在mₐ=20 GeV时为0.4 pb，mₐ=85 GeV时为0.05 pb。
英文摘要
A search for a Lorentz-boosted pseudoscalar resonance $a$ in the mass range between 20 GeV and 85 GeV, produced in association with a top-antitop quark pair and decaying into a $τ$-lepton pair, is presented. Both $τ$-leptons are reconstructed in the hadronic decay mode. The boosted production of $a$ results in a small angular separation between its decay products, requiring the use of dedicated boosted di-$τ$ objects with custom reconstruction, energy calibration, and identification procedures. The analysis uses proton-proton collision data at a centre-of-mass-energy of $\sqrt{s}=13$ TeV collected with the ATLAS detector at the Large Hadron Collider, corresponding to an integrated luminosity of 140 fb$^{-1}$. No significant deviation is observed over the expected Standard Model background, and a model independent upper limit of 0.19 fb is placed at the 95% confidence level on the visible cross-section. Limits on $σ(t\bar{t}a) \times BR(a \to ττ)$ are also obtained for a Two-Higgs-Doublet Model signal scenario, ranging from 0.4 pb at $m_a=20$ GeV to 0.05 pb at $m_a=85$ GeV.
Comments45 pages in total, author list starting page 28, 7 figures, 5 tables, submitted to JHEP. All figures including auxiliary figures are available at http://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HMBS-2024-24
