AI 中文总结
ATLAS利用13 TeV与13.6 TeV共196 fb⁻¹数据，改进b\bar{b}τ⁺τ⁻末态非共振HH产生分析，测得μ_HH与SM一致，约束了希格斯自耦合，同时验证了分析策略的可靠性。
AI 中文摘要
利用2015-2023年期间欧洲核子中心大型强子对撞机上ATLAS探测器记录的质心系能量√s=13 TeV和13.6 TeV下的质子-质子碰撞数据，分别为140 fb⁻¹和56 fb⁻¹，开展了b\bar{b}τ⁺τ⁻末态中非共振希格斯玻色子对（HH）产生的搜寻。相较于ATLAS此前对同一末态的搜寻，本次分析得益于13.6 TeV下采集的额外数据集，以及事例重建和分析技术两方面的改进。测得希格斯玻色子对产生的截面对标准模型（SM）预言的比值μ_HH=2.6⁺¹.⁴₋₁.₀，与SM预期一致。这对应于无HH产生的仅本底假设下，观测到的（预期的）显著性为2.6（1.2）个标准偏差；相对于SM预言的显著性为1.65个标准偏差。在假设所有其他希格斯玻色子耦合均取SM值的前提下，观测到的（预期的）希格斯玻色子自耦合修正因子的95%置信区间为κ_λ∈[-3.4,1.6]∪[5.5,10.1]（κ_λ∈[-1.7,8.5]）。作为分析策略的验证，采用相同的事例选择在同一末态下对ZH和ZZ过程进行测量，相对于仅本底预言，观测到的（预期的）显著性分别为3.5（2.4）和1.8（2.7）个标准偏差。
英文摘要
A search for non-resonant Higgs boson pair production (HH) in the $b\bar{b}τ^+τ^-$ final state is performed using 140 $fb^{-1}$ and 56 $fb^{-1}$ of proton-proton collision data at centre-of-mass energies of $\sqrt{s}$ = 13 TeV and 13.6 TeV, respectively, recorded by the ATLAS detector during 2015-2023 at the CERN Large Hadron Collider. Relative to the previous ATLAS searches in the same final state, the analysis benefits from the additional dataset collected at 13.6 TeV and from improvements in both event reconstruction and analysis techniques. The Higgs boson pair production cross-section divided by the Standard Model (SM) prediction is found to be $μ_{HH}= 2.6^{+1.4}_{-1.0}$, consistent with the SM expectation. This corresponds to an observed (expected) significance of 2.6 (1.2) standard deviations over the background-only hypothesis of no HH production and 1.65 standard deviations with respect to the SM prediction. Under the assumption that all other Higgs boson couplings take their SM values, the observed (expected) 95% confidence level interval for the Higgs boson self-coupling modifier is found to be $κ_λ \in [-3.4, 1.6] \cup [5.5, 10.1]$ ($κ_λ \in[-1.7, 8.5]$). As a validation of the analysis strategy, measurements of the ZH and ZZ processes are performed in the same final state using the same event selection, yielding observed (expected) significances of 3.5 (2.4) and 1.8 (2.7) standard deviations, respectively, relative to the background-only prediction.
Comments65 pages in total, author list starting page 48, 14 figures, 5 tables, submitted to EPJC. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGP-2024-37/
