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arXiv · 2510.01928

Gamow shell model description of exceptional point in $^7$Li

David Cardona Ochoa·Marek Płoszajczak·Nicolas Michel
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Abstract

We report the first identification of an exceptional point (EP) within the Gamow Shell Model in the Coupled Channels representation (GSM-CC). In the spectrum of $^{7}$Li, an EP is found for the $5/2^-$ doublet, where the two states coalesce in both energy and width, the phase rigidity vanishes, and the S-matrix develops a double pole. These features manifest directly in observables: the elastic cross section acquires a split-peak structure, and the phase shift shows a single $2\pi$ jump. This work demonstrates that GSM-CC provides a powerful framework to explore EP phenomena in nuclei and their experimental signatures.

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David Cardona Ochoa, Marek Płoszajczak, Nicolas Michel. 2025-10-02. Gamow shell model description of exceptional point in $^7$Li. https://doi.org/10.1051/epjconf/202534201023

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