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How threshold effects in spectroscopic factors influence heavy-ion knockout reactions

Journal Article · · Physics Letters. B
A two-decade-old puzzle in heavy-ion one-nucleon knockout reactions is the strong correlation between the reduction factor RS = σexpth and the Fermi surface asymmetry ΔS. Theoretical cross sections typically rely on spectroscopic factors (SFs) from shell model (SM) calculations, which neglect continuum coupling effects. Here, we employ the Gamow shell model (GSM), which explicitly incorporates continuum coupling, to compute SFs for p-shell nuclei and predict corresponding theoretical cross sections. Systematic calculations demonstrate that using GSM-derived SFs substantially reduces discrepancies between theoretical and experimental results. This improvement is particularly significant for deeply bound nucleon knockout in nuclei near the dripline, where traditional SM-based calculations fall short. As a result, using GSM SFs, the ratio Rs exhibits no pronounced dependence on ΔS. Furthermore, both the ratio of GSM SFs to SM SFs and their corresponding reaction cross sections ratios exhibit a strong ΔS dependence. We have also compared GSM SFs and cross sections with those from the no-core shell model calculations, giving a similar pronounced sensitivity to ΔS. Detailed analysis attributes these correlations to threshold effects for SFs in weakly bound systems. Overall, incorporating continuum coupling via GSM enhances the reliability of SF predictions for exotic, weakly bound nuclei and provides key insights toward resolving the enduring puzzle in heavy-ion knockout reactions from a nuclear structure perspective.
Research Organization:
East Texas A & M Univ., Commerce, TX (United States)
Sponsoring Organization:
USDOE Office of Science (SC), Nuclear Physics (NP)
Grant/Contract Number:
FG02-08ER41533; SC0026074
Other Award/Contract Number:
25JRRA467
2024YFE0109800
2024YFE0109802
2023YFA1606403
XDB34000000
12121005
12175281
12205340
12347106
OSTI ID:
3021141
Journal Information:
Physics Letters. B, Journal Name: Physics Letters. B Vol. 873; ISSN 0370-2693
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

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