通过Drell-Yan产生中的角系数探测CP破坏效应
Probing the CP violation effects via the angular coefficients in Drell-Yan production
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中文总结 AI 辅助
该研究在SMEFT框架下分析Drell-Yan产生的角系数，发现A₆、A₇对CP破坏偶极相互作用灵敏，结合ATLAS和CMS测量可约束相关威尔逊系数，HL-LHC能进一步提升灵敏度。
中文摘要 AI 辅助
标准模型（SM）中，Drell-Yan产生里的naive-T奇异性角系数A₅至A₇被高度压低，使其成为探测超出标准模型的CP破坏相互作用的灵敏探针。我们在标准模型有效场论（SMEFT）框架下研究这些可观测量，聚焦于六维电弱算符和色磁夸克偶极算符。由于其手征翻转结构，CP破坏偶极相互作用的主导贡献出现在O(1/Λ⁴)阶，源于电弱偶极与色磁偶极振幅的干涉。我们发现，在双轻子横动量较高的区域，偶极贡献被增强，灵敏度主要由A₆和A₇驱动，而A₅基本不敏感。结合ATLAS和CMS的测量结果，当Λ=1 TeV时，我们将威尔逊系数的CP破坏偶极组合约束在O(0.1)水平。假设高亮度大型强子对撞机（HL-LHC）的不确定性由统计主导，灵敏度可提升至O(10⁻³)水平。我们的结果表明，A₆和A₇是强子对撞机中CP破坏偶极相互作用的互补探针。
英文摘要
The naive-$T$-odd angular coefficients $A_5$--$A_7$ in Drell--Yan production are highly suppressed in the Standard Model (SM), making them sensitive probes of CP-violating interactions beyond the SM. We study these observables within the Standard Model Effective Field Theory (SMEFT), focusing on dimension-six electroweak and chromomagnetic quark dipole operators. Due to their chirality-flipping structure, the leading contributions from CP-violating dipole interactions arise at $\mathcal{O}(1/Λ^4)$ through the interference between electroweak and chromomagnetic dipole amplitudes. We find that the sensitivity is primarily driven by $A_6$ and $A_7$ in the high dilepton transverse momentum region, where the dipole contributions are enhanced, while $A_5$ remains largely insensitive. Combining the ATLAS and CMS measurements, we constrain the CP-violating dipole combinations of Wilson coefficients at the $\mathcal{O}(0.1)$ level for $Λ=1~{\rm TeV}$. Assuming statistically dominated uncertainties at the HL-LHC, the sensitivity can be improved to the $\mathcal{O}(10^{-3})$ level. Our results highlight $A_6$ and $A_7$ as complementary probes of CP-violating dipole interactions at hadron colliders.
