标题： 直接暗物质搜索中次级有效算符的中子电弱偶极矩约束 显示英文标题

标题： Constraints from the Neutron EDM on Subleading Effective Operators for Direct Dark Matter Searches

摘要： 暗物质（DM）与核子在直接搜索实验中相关的相互作用可以使用一个伽利略不变的、非相对论的有效场理论（NREFT）以模型无关的方式进行组织。 在这里，将相互作用按动量转移$\vec{q}$和暗物质速度$\vec{v}$的幂次展开。 这种方法会产生许多算符。 可能最重要的次主导算符在$T$下是奇的，因此只能存在于具有$CP$破坏相互作用的理论中。 我们考虑了两种这样的算符，在文献中称为$\mathcal{O}_{10}$和$\mathcal{O}_{11}$，在具有中性自旋$-0$介子的简化模型中；耦合被选择使得在$\vec{v} \rightarrow 0$下仍然存在的主导自旋无关（SI）算符的系数在树图级别消失。 然而，它在微扰理论的下一级通常会被诱导出来。 我们对涉及$T-$奇数算符的相互作用与相应的环状诱导 SI 贡献之间的散射事件数量进行了数值比较。 我们发现，对于“最大”$CP$破坏，前者可以超过后者。 然而，在我们考虑的三个模型中的两个中，中子的电偶极矩（nEDM）在二环阶被诱导出来。 我们发现，nEDM 的实验限制通常会导致由${\mathcal O}_{10}$引起的速率无法被探测到。 另一方面，导致${\mathcal O}_{11}$系数不为零的模型不会诱导nEDM。 显示英文摘要

摘要： Interactions between Dark Matter (DM) and nucleons relevant for direct search experiments can be organised in a model independent manner using a Galiliean invariant, non--relativistic effective field theory (NREFT). Here one expands the interactions in powers of the momentum transfer $\vec{q}$ and DM velocity $\vec{v}$. This approach generates many operators. The potentially most important subleading operators are odd under $T$, and can thus only be present in a theory with $CP$ violating interactions. We consider two such operators, called $\mathcal{O}_{10}$ and $\mathcal{O}_{11}$ in the literature, in simplified models with neutral spin$-0$ mediators; the couplings are chosen such that the coefficient of the leading spin independent (SI) operator, which survives for $\vec{v} \rightarrow 0$, vanishes at tree level. However, it is generically induced at the next order in perturbation theory. We perform a numerical comparison of the number of scattering events between interactions involving the $T-$odd operators and the corresponding loop induced SI contributions. We find that for ''maximal'' $CP$ violation the former can dominate over the latter. However, in two of the three models we consider, an electric dipole moment of the neutron (nEDM) is induced at two--loop order. We find that the experimental bound on the nEDM typically leads to undetectably small rates induced by ${\mathcal O}_{10}$. On the other hand, the model leading to a nonvanishing coefficient of ${\mathcal O}_{11}$ does not induce an nEDM.