发表机构
INFN, Sezione di Trieste（意大利国家核物理研究所的里雅斯特分部）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究高质量Drell-Yan中PDF效应对SMEFT约束的影响，通过联合拟合SMEFT威尔逊系数和PDF微扰参数，发现其灵敏度强烈依赖味，角信息可减少简并，表明PDF不确定性相关性在味空间不均一，需依味评估。
AI 中文摘要
高质量Drell-Yan双轻子产生是标准模型有效场论（SMEFT）中半轻子四费米子算符最灵敏的探针之一，其贡献随能量增长。同时，这些测量也在大x区域约束部分子分布函数（PDFs），该区域PDF不确定性会模拟或掩盖新物理效应。本文通过联合拟合SMEFT威尔逊系数和PDF微扰参数，研究PDF分析对SMEFT约束的影响如何依赖于有效算符的夸克味结构。发现PDF分析会导致SMEFT灵敏度强烈依赖味的退化，当前数据和HL-LHC预测中均如此。涉及第一代夸克的算符退化最大，涉及更重夸克味的算符受影响较小但有不可忽略的依赖算符的变化。作为分析副产品，得到了通过分析SMEFT效应在PDF部分引起的变化估计。还表明角信息是减少SMEFT方向间以及SMEFT效应与允许的PDF变形间简并的重要手段。这些结果表明PDF不确定性在高能SMEFT拟合中的相关性在味空间中并非均匀，必须以依赖味的方式评估。
英文摘要
High-mass Drell-Yan dilepton production provides one of the most sensitive probes of semileptonic four-fermion operators in the Standard Model Effective Field Theory (SMEFT), thanks to the energy growth of the corresponding contributions. At the same time, these measurements also constrain parton distribution functions (PDFs) in the large-$x$ region, where PDF uncertainties can mimic or obscure smooth new-physics effects. In this work we study how the impact of PDF profiling on SMEFT constraints depends on the quark-flavour structure of the effective operators, by performing a joint fit of SMEFT Wilson coefficients and PDF nuisance parameters. We find that PDF profiling induces a strongly flavour-dependent degradation of the SMEFT sensitivity, both with current data and in HL-LHC projections. The largest broadenings occur for operators involving first-generation quarks, whose effects are correlated with the high-$x$ valence-quark luminosities that dominate the high-mass spectrum. Operators involving heavier quark flavours are less affected, although with non-negligible operator-dependent variations. As a byproduct of our analysis, we obtain an estimate on the changes induced in the PDF sector by profiling SMEFT effects. We also show that angular information provides an important handle to reduce degeneracies among SMEFT directions and between SMEFT effects and allowed PDF deformations. These results demonstrate that the relevance of PDF uncertainties in high-energy SMEFT fits is not uniform across flavour space, and must be assessed in a flavour-dependent way.
Comments33 pages, v2: version submitted to JHEP. Added link to publicly available approximate profiled chi2
