Measurements of nuclear spin-dependent parity-violating (NSD-PV) effects provide an excellent opportunity to test nuclear models and to search for physics beyond the Standard Model. Molecules possess closely spaced states with opposite parity which may be easily tuned to degeneracy to greatly enhance the observed parity-violating effects. A high-sensitivity measurement of NSD-PV effects using light triatomic molecules is in preparation [E. B. Norrgard et al., Commun. Phys. 2, 77 (2019)]. Importantly, by comparing these measurements in light nuclei with prior and ongoing measurements in heavier systems, the contribution to NSD-PV from $Z^0$-boson exchange between the electrons and the nuclei may be separated from the contribution of the nuclear anapole moment. Furthermore, light triatomic molecules offer the possibility to search for new particles, such as the postulated $Z^{\prime }$ boson. In this work, we detail a sensitive measurement scheme and present high-accuracy molecular and nuclear calculations needed for interpretation of NSD-PV experiments on triatomic molecules composed of light elements, Be, Mg, N, and C. The ab initio nuclear structure calculations, performed within the no-core shell model provide a reliable prediction of the magnitude of different contributions to the NSD-PV effects in the four nuclei. These results differ significantly from the predictions of the standard single-particle model and highlight the importance of including many-body effects in such calculations. In order to extract the NSD-PV contributions from measurements, a parity-violating interaction parameter $W_{\text{PV}}$, which depends on the molecular structure, needs to be known with a high accuracy. We have calculated these parameters for the triatomic molecules of interest using the relativistic coupled-cluster approach. In order to facilitate the interpretation of future experiments we provide uncertainties on the calculated parameters. A scheme for measurement using laser-cooled polyatomic molecules in a molecular fountain is presented, along with an estimate of the expected sensitivity of such an experiment. This experimental scheme, combined with the presented state-of-the-art calculations, opens exciting prospects for a measurement of the anapole moment and the PV effects due to the electron-nucleon interactions with unprecedented accuracy and for a new path towards detection of signatures of physics beyond the Standard Model.

中文翻译：

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轻多原子分子的核自旋依赖性奇偶违反效应

测量核自旋相关的违反奇偶性（NSD-PV）效应，为测试核模型和寻找标准模型以外的物理提供了绝佳的机会。分子具有彼此相反的奇偶性的紧密间隔的状态，可以容易地将其调整为简并性，从而大大增强观察到的违反奇偶性的作用。正在准备使用轻质三原子分子对NSD-PV效应进行高灵敏度的测量[EB Norrgard等人。，Commun。物理 2，77（2019）]。重要的是，通过将光核中的这些测量值与较重系统中先前和正在进行的测量值进行比较，可以得出NSD-PV的贡献${ž}^0$电子与核之间的玻色子交换可能与核偶极矩的贡献分开。此外，轻质三原子分子提供了寻找新粒子的可能性，例如${ž}^{\prime }$玻色子。在这项工作中，我们详细介绍了一种灵敏的测量方案，并提出了用于解释由轻元素Be，Mg，N和C组成的三原子分子的NSD-PV实验所需的高精度分子和核计算。从头算核结构计算在无核壳模型中执行的，提供了对四个核中NSD-PV效应的不同贡献量的可靠预测。这些结果与标准单粒子模型的预测明显不同，并突出了在这种计算中包括多体效应的重要性。为了从测量中提取NSD-PV贡献，违反奇偶性的交互参数${\mathrm{w\; ^}}_{\text{光伏}}$取决于分子结构的，需要高度准确地知道。我们已经使用相对论耦合簇方法为目标三原子分子计算了这些参数。为了便于将来的实验解释，我们提供了计算参数的不确定性。提出了一种在分子喷泉中使用激光冷却的多原子分子进行测量的方案，以及对此类实验的预期灵敏度的估计。该实验方案，结合当前的最新技术，为测量偶极矩和PV效应提供了令人振奋的前景，这是由于电子-核子相互作用以前所未有的精度实现的，并且为检测特征码提供了新途径超越标准模型的物理学。