In the electroweak sector of the Standard Model, CP violation arises through a very particular interplay between the three quark generations, as described by the Cabibbo--Kobayashi--Maskawa (CKM) mechanism and the single Jarlskog invariant $J_4$. Once generalized to the Standard Model Effective Field Theory (SMEFT), this peculiar pattern gets modified by higher-dimensional operators, whose associated Wilson coefficients are usually split into CP-even and odd parts. However, CP violation at dimension four, i.e., at the lowest order in the EFT expansion, blurs this distinction: any Wilson coefficient can interfere with $J_4$ and mediate CP violation. In this paper, we study such interferences at first order in the SMEFT expansion, $\mathcal{O}(1/Λ^2)$, and we capture their associated parameter space via a set of 1551 linear CP-odd flavor invariants. This construction describes both new, genuinely CP-violating quantities as well as the interference between $J_4$ and CP-conserving ones. We call this latter possibility \textit{opportunistic CP violation}. Relying on an appropriate extension of the matrix rank to Taylor expansions, which we dub \emph{Taylor rank}, we define a procedure to organize the invariants in terms of their magnitude, so as to retain only the relevant ones at a given precision. We explore how this characterization changes when different assumptions are made on the flavor structure of the SMEFT coefficients. Interestingly, some of the CP-odd invariants turn out to be less suppressed than $J_4$, even when they capture opportunistic CPV, demonstrating that CP-violation in the SM, at dimension 4, is \textit{accidentally small.}
Connecting $t$-channel Dark Matter Models to the Standard Model Effective Field Theory
Institute of Physics, University of Freiburg（弗莱堡大学物理研究所）；Dipartimento di Fisica e Geologia, Università degli studi di Perugia（佩鲁贾大学物理与地质学系）；INFN, Sezione di Perugia（意大利国家核物理研究所佩鲁贾分部）
本文在标准模型有效场论（SMEFT）的模型无关框架下，对电子-离子对撞机（EIC）对通道$ep\to τX$中带电轻子味破坏（CLFV）的潜在敏感性进行了全面分析。我们计算相关的横截面，以领先的QCD和电弱修正，并进行模拟的信号和SM背景事件在各种$τ$衰变通道，建议简单的削减，以提高相关的估计效率。为了评估EIC在$τ$ - $e$跃迁中的发现潜力，我们研究了这种物理学的其他探测器在广泛的能量尺度上的灵敏度，从大型强子对撞机的$pp \to e τX$到$B$介子和$τ$轻子的衰变，如$τ\to e γ$，$τ\to e \ell^+ \ell^-$，以及至关重要的强子模式$τ\to e Y$与$Y \in \{ π, K, ππ, K π, ...\}$。我们发现，涉及轻夸克的电弱偶极和四费米子半轻子算符已经受到$τ$衰变的强烈约束，而涉及$c$和$b$夸克的算符则为EIC提供了更有希望的发现潜力。三个模型的leptoquark的分析证实了预期的SMEFT结果的基础上。我们还确定了未来的方向，需要最大限度地达到的EIC在CLFV搜索：这些包括优化的$τ$标签在强子通道，通过标记$b$和$c$喷流在最终状态的背景抑制的探索，并通过打开所有的SMEFT耦合，这可能会揭示新的发现窗口的EIC。
Institute for Nuclear Theory, University of Washington（华盛顿大学核理论研究所）；Northwestern University（西北大学）；KEK Theory Center, IPNS, KEK（高能加速器研究机构理论中心）；Theoretical Division, Los Alamos National Laboratory（洛斯阿拉莫斯国家实验室理论部）
Probing the CP violation effects via the angular coefficients in Drell-Yan production
Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Center for High Energy Physics, Peking University（北京大学高能物理中心）
