The precession of particle spin in spherical symmetric spacetimes

Abstract In this work, we will explore the precession of particle spins in spherical spacetimes. We first argue that the geometrical optics (WKB) approximation is insufficient, due to the absence of a glory spot in the backward scattering of massless particles, making an analysis of spin precession...

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Main Authors: Xiankai Pang, Qingquan Jiang, Yunchuan Xiang, Gao-Ming Deng
Format: Article
Language:English
Published: SpringerOpen 2025-02-01
Series:European Physical Journal C: Particles and Fields
Online Access:https://doi.org/10.1140/epjc/s10052-025-13894-8
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author Xiankai Pang
Qingquan Jiang
Yunchuan Xiang
Gao-Ming Deng
author_facet Xiankai Pang
Qingquan Jiang
Yunchuan Xiang
Gao-Ming Deng
author_sort Xiankai Pang
collection DOAJ
description Abstract In this work, we will explore the precession of particle spins in spherical spacetimes. We first argue that the geometrical optics (WKB) approximation is insufficient, due to the absence of a glory spot in the backward scattering of massless particles, making an analysis of spin precession necessary. We then derive the precession equation assuming the spin is parallel transported, which is supported by the sub-leading order of the WKB approximation. The precession equation applies to both massless and massive particles. For particles moving at the speed of light, we show that spin is always reversed after backward scattering in any spherically symmetric spacetime, confirming the absence of a glory spot for massless particles. Finally, we solve the precession equation for Schwarzschild and Reissner–Nordström spacetimes and discuss the spin precession of massive particles, particularly in the non-relativistic limit. We find that, in Schwarzschild spacetime, the spin precession for particles moving with very small velocities compared to the speed of light depends only on the deflection angle, while in Reissner–Nordström spacetime, it also depends on the black hole charge, as revealed by the expansion derived from the strong lensing approximation.
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series European Physical Journal C: Particles and Fields
spelling doaj-art-b45cbbb1bf05471d84efc13770e0adf12025-08-20T02:15:08ZengSpringerOpenEuropean Physical Journal C: Particles and Fields1434-60522025-02-0185211510.1140/epjc/s10052-025-13894-8The precession of particle spin in spherical symmetric spacetimesXiankai Pang0Qingquan Jiang1Yunchuan Xiang2Gao-Ming Deng3School of Physics and Astronomy, China West Normal UniversitySchool of Physics and Astronomy, China West Normal UniversitySchool of Physics and Astronomy, China West Normal UniversitySchool of Physics and Astronomy, China West Normal UniversityAbstract In this work, we will explore the precession of particle spins in spherical spacetimes. We first argue that the geometrical optics (WKB) approximation is insufficient, due to the absence of a glory spot in the backward scattering of massless particles, making an analysis of spin precession necessary. We then derive the precession equation assuming the spin is parallel transported, which is supported by the sub-leading order of the WKB approximation. The precession equation applies to both massless and massive particles. For particles moving at the speed of light, we show that spin is always reversed after backward scattering in any spherically symmetric spacetime, confirming the absence of a glory spot for massless particles. Finally, we solve the precession equation for Schwarzschild and Reissner–Nordström spacetimes and discuss the spin precession of massive particles, particularly in the non-relativistic limit. We find that, in Schwarzschild spacetime, the spin precession for particles moving with very small velocities compared to the speed of light depends only on the deflection angle, while in Reissner–Nordström spacetime, it also depends on the black hole charge, as revealed by the expansion derived from the strong lensing approximation.https://doi.org/10.1140/epjc/s10052-025-13894-8
spellingShingle Xiankai Pang
Qingquan Jiang
Yunchuan Xiang
Gao-Ming Deng
The precession of particle spin in spherical symmetric spacetimes
European Physical Journal C: Particles and Fields
title The precession of particle spin in spherical symmetric spacetimes
title_full The precession of particle spin in spherical symmetric spacetimes
title_fullStr The precession of particle spin in spherical symmetric spacetimes
title_full_unstemmed The precession of particle spin in spherical symmetric spacetimes
title_short The precession of particle spin in spherical symmetric spacetimes
title_sort precession of particle spin in spherical symmetric spacetimes
url https://doi.org/10.1140/epjc/s10052-025-13894-8
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