利用中子星自旋下降测量中子电偶极矩
Measuring the electric dipole moment of the neutron using neutron star spin-down
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中文总结 AI 辅助
该研究利用毫秒脉冲星PSR J0437-4715，结合中子星结构、射电偏振等数据，提出源特异性框架，得到中子电偶极矩及相关参数的约束，可用于测试非标准CP奇异性辐射通道。
中文摘要 AI 辅助
中子电偶极矩（nEDM）是超出标准模型的CP破坏的灵敏探针。我们开发了一种源特异性框架，用于利用附近的毫秒脉冲星PSR J0437-4715约束CP奇异性的中子结构。通过质量和半径测量构建恒星结构模型，并估算极化的内壳中子储库。宽带射电偏振测量提供了由传播信息得到的表面磁场后验分布，这是常规P$\boldsymbol{\textit{P}}$磁场估计无法得到的，同时利用已发表的NICER热点约束来测试低阶表面磁场几何结构，并分离出进入电磁力矩的偶极分量。这些输入通过当前的自旋下降预算（包括电磁和引力波损失）进行传播。剩余的正残差首先被解释为未屏蔽的电偶极辐射基准。随后，内壳和磁层的屏蔽作用催生了一种有效的CP奇异性磁四极通道。在采用的屏蔽、相干性和有效模式频率规定的条件下，正残差分支给出90%分位数界$|M_n^0|<7.47\times10^{-38}$ e cm$^2$。结合采用的QCD转换系数，这对应于$|\bar{\theta}|<2.99\times10^{-9}$和等效的$|d_n|<4.42\times10^{-25}$ e cm。尽管该结果弱于实验室nEDM极限，但它证明了如何将源特异性中子星结构、射电传播、磁场几何和自旋下降能量学结合起来，以测试非标准CP奇异性辐射通道。
英文摘要
The neutron electric dipole moment (nEDM) is a sensitive probe of CP violation beyond the Standard Model. We develop a source-specific framework for constraining CP-odd neutron structure using the nearby millisecond pulsar PSR J0437-4715. Mass and radius measurements are used to construct a stellar-structure model and estimate the polarized inner-crust neutron reservoir. Wideband radio polarimetry provides a propagation-informed surface-field posterior that is not obtained from the conventional $P\dot P$ magnetic-field estimate, while published NICER hot-region constraints are used to test low-order surface-field geometries and isolate the dipolar component entering the electromagnetic torque. These inputs are propagated through a present-day spin-down budget including electromagnetic and gravitational-wave losses. The remaining positive residual is first interpreted as an unscreened electric-dipole-radiation benchmark. Crustal and magnetospheric screening then motivate an effective CP-odd magnetic-quadrupole channel. Conditional on the adopted screening, coherence, and effective-mode-frequency prescriptions, the positive-residual branch gives a 90th-percentile bound $|M_n^0|<7.47\times10^{-38}$ e cm$^2$. With the adopted QCD conversion coefficients, this corresponds to $|\barθ|<2.99\times10^{-9}$ and an equivalent $|d_n|<4.42\times10^{-25}$ e cm. Although weaker than laboratory nEDM limits, the result demonstrates how source-specific neutron-star structure, radio propagation, magnetic geometry, and spin-down energetics can be combined to test nonstandard CP-odd radiation channels.
