发表机构
School of Physics, Huazhong University of Science and Technology（华中科技大学物理学院）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究将引力的Pontryagin和Nieh-Yan拓扑项约化为类空超曲面，经SVT分解得到四种螺旋度密度，研究其展开并应用于多种引力模型。
AI 中文摘要
引力中的螺旋度是一个多面概念，文献中存在若干不等价定义。本研究将拓扑Pontryagin项和Nieh-Yan项约化为恒定时间类空超曲面。值得注意的是，在线性水平应用SVT分解后，我们得到四种不同的螺旋度密度：源自Nieh-Yan项的螺旋度密度，根据其源自矢量模式还是张量模式，被称为自旋1和自旋2的引力磁性螺旋度密度；源自Pontryagin项的螺旋度密度，根据相应的模式贡献，被称为自旋1和自旋2的引力电流螺旋度密度。我们研究了这些螺旋度泛函的模式和多极展开，并将其应用于领头阶牛顿两体系统、弱场 boosted Kerr、局域定义的慢变gyratonic pp-波模型以及线性化引力Hopfion。
英文摘要
Helicity in gravity is a multifaceted concept, and several inequivalent definitions exist in the literature. In this work, we reduce the topological Pontryagin and Nieh-Yan terms to a constant time spacelike hypersurface. Remarkably, upon applying the SVT decomposition at the linearized level, we obtain four distinct helicity densities. The helicity density arising from the Nieh-Yan term is termed the spin-1 and spin-2 gravitomagnetic helicity density, depending on whether it originates from vector or tensor modes. Meanwhile, the helicity density arising from the Pontryagin term is termed the spin-1 and spin-2 gravito-current helicity density, according to the corresponding mode contributions. We study the mode and multipole expansions of these helicity functionals and apply them to leading order Newtonian two-body systems, weak field boosted Kerr, a locally defined slowly varying gyratonic pp-wave model, and a linearized gravitational Hopfion.
Comments54 pages, 3 figures
