Strong Angular-Momentum-Coupling Dependence of Atomic Decay Angular Distributions in a Hybrid LS/LSJ Framework
Abstract
State production and its subsequent decay can each require a different angular-momentum coupling treatment. Although long recognized, this distinction is often overlooked in the two-step model, where LS coupling is traditionally applied to both production and decay (LS/LS), even when the decay requires LSJ coupling. We introduce a hybrid LS/LSJ formulation that uses established angular-momentum recoupling theory to project the initial LS alignment onto the fine-structure J states, evaluates their decay in LSJ coupling, and, for well-separated J levels, sums their contributions incoherently. The 1s2s2p 4 PJ manifold produced by single-electron capture in C4+(1s2s 3 S)+He collisions provides a good test case, with ML-resolved theoretical production cross sections and absolute measurements of the Auger single-differential cross section available. Using the same LS production cross sections in both treatments, we find that the hybrid LS/LSJ treatment strongly suppresses and can even invert the Auger anisotropy relative to the traditional LS/LS treatment, substantially improving agreement with the measurements. Such an incoherent hybrid formulation provides the appropriate framework when LS coupling governs the initial interaction dynamics while well-separated fine-structure levels require an LSJ description of the decay.
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BibTeX
@misc{zouros2026strong,
title = {{Strong Angular-Momentum-Coupling Dependence of Atomic Decay Angular Distributions in a Hybrid $\mathbfLS/LSJ$ Framework}},
author = {Theo J. M. Zouros},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2609.25865},
eprint = {2609.25865},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.25865},
}
RIS
TY - UNPB
TI - Strong Angular-Momentum-Coupling Dependence of Atomic Decay Angular Distributions in a Hybrid LS/LSJ Framework
AU - Theo J. M. Zouros
PY - 2026
DA - 2026/10/01
PB - arXiv
DO - 10.48550/arxiv.2609.25865
UR - https://arxiv.org/abs/2609.25865
AB - State production and its subsequent decay can each require a different angular-momentum coupling treatment. Although long recognized, this distinction is often overlooked in the two-step model, where LS coupling is traditionally applied to both production and decay (LS/LS), even when the decay requires LSJ coupling. We introduce a hybrid LS/LSJ formulation that uses established angular-momentum recoupling theory to project the initial LS alignment onto the fine-structure J states, evaluates their decay in LSJ coupling, and, for well-separated J levels, sums their contributions incoherently. The 1s2s2p ^4 P_J manifold produced by single-electron capture in C^4+(1s2s ^3 S)+He collisions provides a good test case, with M_L-resolved theoretical production cross sections and absolute measurements of the Auger single-differential cross section available. Using the same LS production cross sections in both treatments, we find that the hybrid LS/LSJ treatment strongly suppresses and can even invert the Auger anisotropy relative to the traditional LS/LS treatment, substantially improving agreement with the measurements. Such an incoherent hybrid formulation provides the appropriate framework when LS coupling governs the initial interaction dynamics while well-separated fine-structure levels require an LSJ description of the decay.
ER -