AI 中文总结
本文利用ATLAS探测器在13 TeV质子碰撞中通过H→γγ在壳干涉直接测量希格斯玻色子总宽度，无需耦合假设，设定了95%置信水平下307 MeV的上限，约为标准模型预言的75倍。
AI 中文摘要
希格斯玻色子的总衰变宽度$\Gamma_H$包含了其所有衰变模式；任何衰变到标准模型（SM）之外粒子的过程都会使$\Gamma_H$高于SM预言值4.1 MeV。本文报道了对$\Gamma_H$的直接在壳测量，利用共振$H \to \gamma\gamma$振幅与连续双光子本底之间的干涉，这种干涉会以使$\Gamma_H$相关的方式扭曲双光子不变质量分布，且无需对希格斯玻色子耦合做任何假设。利用LHC Run 2期间ATLAS探测器记录的$\sqrt{s}=13$ TeV下140 fb$^{-1}$的质子-质子碰撞数据，在95%置信水平下设置了$\Gamma_H < 307$（期望258）MeV的观测（期望）上限，约为SM预言的75（63）倍。与对$\Gamma_H$的间接在壳外约束不同，本测量不依赖于对希格斯玻色子耦合的假设，为探测希格斯玻色子可能衰变到新粒子提供了新颖的互补探针。
英文摘要
The total decay width of the Higgs boson, $Γ_H$, encodes all of its decay modes; any decay into particles beyond the Standard Model (SM) would increase $Γ_H$ above the SM prediction of 4.1 MeV. In this Letter, a direct, on-shell measurement of $Γ_H$ is reported, exploiting the interference between the resonant $H \to γγ$ amplitude and the continuum diphoton background, which distorts the diphoton invariant mass distribution in a way that depends on $Γ_H$ without requiring assumptions on the Higgs boson couplings. Using 140 fb$^{-1}$ of proton-proton collision data at $\sqrt{s}=13$ TeV recorded by the ATLAS detector during Run 2 of the LHC, an observed (expected) upper limit of $Γ_H < 307$ (258) MeV is set at 95% confidence level, approximately 75 (63) times the SM prediction. Unlike indirect off-shell constraints on $Γ_H$, this measurement does not rely on assumptions about the Higgs boson couplings, providing a novel complementary probe sensitive to potential Higgs boson decays into new particles.
Comments33 pages in total, author list starting page 16, 3 figures, 0 tables, submitted to Phys. Rev. Lett. All figures including auxiliary figures are available at https://atlas.web.cern.ch/Atlas/GROUPS/PHYSICS/PAPERS/HIGP-2024-12
