为评估标准模型有效场论（Standard Model Effective Field Theory，SMEFT）展开中高阶项的相关性，我们考察了四种新物理模型及其对Drell-Yan截面的影响。在这四种模型中，一种标量模型对Drell-Yan过程无影响；一种费米子模型看似产生动量展开，实则属于真空期望值展开，因此对该过程仅有标称效应。其余两种——轻子夸克模型和Z'模型——表现出动量展开特性。在将这些模型匹配到十维算符后，我们研究了在假设的有效场论拟合中纳入八维和十维算符以拟合完整紫外模型时，会对拟合结果产生何种影响。我们同时采用自上而下方法，以及SMEFT自下而上方法的一种极有限近似来开展研究，以推断SMEFT完全通用拟合的影响。我们发现，对于耦合更弱的模型，严格的六维拟合就已足够。与之相反，当考虑更强的相互作用或更轻的质量时，纳入八维算符就变得十分必要。不过，这些八维算符的Wilson系数扮演了冗余参数的角色，其最佳拟合值可能与理论预测存在统计上的差异。在我们所考察的耦合最强的理论中（这类理论已被现有数据排除），纳入十维算符后，八维算符系数的测量结果可与理论预测保持一致，此时十维算符系数则充当冗余参数。我们还研究了纳入部分次阶结果（例如六维算符的平方贡献）的影响，发现在部分情况下它们能改善级数的收敛性，而在另一些情况下则会阻碍收敛。
英文摘要：
In order to assess the relevance of higher order terms in the Standard Model Effective Field Theory (SMEFT) expansion we consider four new physics models and their impact on the Drell Yan cross section. Of these four, one scalar model has no effect on Drell Yan, a model of fermions while appearing to generate a momentum expansion actually belongs to the vacuum expectation value expansion and so has a nominal effect on the process. The remaining two, a leptoquark and a Z' model exhibit a momentum expansion. After matching these models to dimension-ten we study how the inclusion of dimension-eight and dimension-ten operators in hypothetical effective field theory fits to the full ultraviolet models impacts fits. We do this both in the top-down approach, and in a very limited approximation to the bottom up approach of the SMEFT to infer the impact of a fully general fit to the SMEFT. We find that for the more weakly coupled models a strictly dimension-six fit is sufficient. In contrast when stronger interactions or lighter masses are considered the inclusion of dimension-eight operators becomes necessary. However, their Wilson coefficients perform the role of nuisance parameters with best fit values which can differ statistically from the theory prediction. In the most strongly coupled theories considered (which are already ruled out by data) the inclusion of dimension-ten operators allows for the measurement of dimension-eight operator coefficients consistent with theory predictions and the dimension-ten operator coefficients then behave as nuisance parameters. We also study the impact of the inclusion of partial next order results, such as dimension-six squared contributions, and find that in some cases they improve the convergence of the series while in others they hinder it.
Complete two-loop Yukawa-induced running of the Higgs-gluon coupling in SMEFT
Karlsruhe Institute of Technology (KIT)（卡尔斯鲁厄理工学院）；Università degli Studi di Padova（帕多瓦大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Padova（意大利国家核物理研究所帕多瓦分部）
Flavorful Lepton-Number-Violating SMEFT: Loop Mixing, $0νββ$ and Rare Meson Decays
Institute of Particle and Nuclear Physics (IPNP), Faculty of Mathematics and Physics, Charles University in Prague（布拉格查理大学数学物理学院粒子与核物理研究所）；Institute of Physics, Silesian University in Opava（奥帕瓦西里西亚大学物理研究所）；Instituto de Física Corpuscular (IFIC), Universitat de València–CSIC（巴伦西亚大学-西班牙国家科学研究委员会粒子物理研究所）；Department of Physics, University of California, Berkeley（加州大学伯克利分校物理学系）
