Nuclear Theory·nucl-th

Friday·November 19, 2021

4 papers—4 primary·0 cross-listed

01
[Submitted on 17 Nov 2021]
Determination of complete experiments using graphs
Y. Wunderlich🇩🇪 · P. Kroenert🇩🇪 · F. Afzal🇩🇪 · A. Thiel🇩🇪
This work presents ideas for the determination of complete experiments using graphs, which are based on a recently published, modified form of Moravcsik's theorem. The lucid representation of complete experiments in terms of graphs, which is at the heart of the theorem, leads to a fully automated procedure that can determine complete experiments for in principle any reaction, i.e. for any number of amplitudes $N$ . For larger $N$ (i.e. $N \geq 4$ ), the sets determined according to Moravcsik's theorem turn out to be slightly overcomplete. A new type of directional graph has been proposed recently, which can decrease the length of the complete sets of observables in some of these cases. The presented results are relevant for reactions with larger numbers of spin-amplitudes, which are at the center of interest in forthcoming measurements, such as single-meson electroproduction $(N = 6)$ , two-meson photoproduction $(N = 8)$ or vector-meson photoproduction $(N = 12)$ .
Comments:
7 pages, 7 figures, 1 table; This article is part of the Proceedings of the "19th International Conference on Hadron Spectroscopy and Structure in memoriam Simon Eidelman (HADRON2021)" held in Mexico City, Mexico, in July 2021; Version 2 has been accepted for publication by Revista Mexicana de Física
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2111.09419 [pdf]
Rev.Mex.Fis.Suppl.(2022)·0 citations
02
[Submitted on 18 Nov 2021]
Application of the single-channel, single-energy AA/PWA method to $K^{+} Λ$ photoproduction
A. Švarc🇭🇷 · Y. Wunderlich🇩🇪 · L. Tiator🇩🇪
The new single-channel, single-energy partial wave analysis method based on a simultaneous use of amplitude and partial wave analysis called AA/PWA, developed and tested on $η$ photoproduction in ref. Svarc et al, PRC 102, 064609 (2020), is applied to the $K^{+} Λ$ photoproduction for the center-of-mass energy range of 1625 MeV $< W <$ 2296 MeV. A complete set of multipoles has been created. The advantages of the method have been confirmed, and a comparison with the only existing single-energy partial wave analysis of $K^{+} Λ$ photoproduction given in refs. Anisovich et al PRL 119 062004 (2017) and Anisovich et al Eur. Phys. J. A 53: 242 (2017) is presented. We confirm the size and shape of Bonn-Gatchina multipoles, but we do not confirm the unambiguous interpretation of the structure in the $M_{1 -}$ multipole as a $N (1880) \frac{1}{2}^{+}$ resonance. The decisive role of the self-consistency of the world database is emphasized.
Comments:
37 pages, 20 Figures, 3 tables
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2111.09587 [pdf]
PRC(2022)·7 citations
03
[Submitted on 18 Nov 2021]
Search for the $α$ + core structure in the ground state bands of $22 \leq Z \leq 42$ even-even nuclei
M. A. Souza · H. Miyake
A systematic analysis of the $α$ + core structure is performed in the ground state bands of even-even nuclei of the $22 \leq Z \leq 42$ region in terms of the Local Potential Model. The $α$ + core interaction is described by the nuclear potential of (1 + Gaussian) $\times$ (W.S. + W.S. $^{3}$ ) shape with 2 free parameters. Properties such as energy levels, reduced $α$ -widths, $B (E 2)$ transition rates and rms charge radii are calculated and compared with experimental data. A good agreement with the experimental data is obtained in general, even for the nuclei without the $α$ + {doubly closed shell core} configuration. The analysis of the selected nuclei in the $22 \leq Z \leq 42$ region indicates that $^{44}$ Ti and $^{94}$ Mo have a greater $α$ -clustering degree in comparison with their respective neighboring nuclei of this set. In addition, the model points to the existence of nuclei without the $α$ + {doubly closed shell core} configuration with a significant $α$ -clustering degree compared to $^{44}$ Ti, $^{60}$ Zn, and $^{94}$ Mo. The study shows that the $α$ + core approach is satisfactorily applicable to nuclei other than those with $α$ -clustering above double-shell closures.
Comments:
20 pages, 8 figures. Accepted for publication in Physical Review C
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2111.09598 [pdf]
PRC(2021)·9 citations
04
[Submitted on 18 Nov 2021]
Charged-particle optical potentials tested by first direct measurement of 59Cu(p,alpha)56Ni reaction
Vlad Avrigeanu · Marilena Avrigeanu
Due consideration of proton optical--model potential (OMP) anomalies at sub-Coulomb energies for medium--weight nuclei is shown to be critical for the analysis of the unprecedented measurement of $^{59}$ Cu $(p, α)^{56}$ Ni reaction cross section at an energy of $\sim$ 6 MeV [Phys. Rev. C {\bf 104}, L042801 (2021)]. The variation in predicted cross sections from standard statistical--model calculations and the cross--section range corresponding to the anomalous proton imaginary--potential depth, for target nuclei off the line of stability, are distinct and well separated. Consequently, the new measurement provides, under unique conditions, tests of proton isoscalar and isovector real--potential components, the anomalous imaginary potential, as well as previous alpha-particle OMP, for nuclei off the line of stability.
Comments:
3 pages, 1 figure, references added and improved manuscript
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2111.09775 [pdf]
PRC(2022)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Determination of complete experiments using graphs

Application of the single-channel, single-energy AA/PWA method to K+Λ photoproduction

Search for the α + core structure in the ground state bands of 22≤Z≤42 even-even nuclei

Charged-particle optical potentials tested by first direct measurement of 59Cu(p,alpha)56Ni reaction

Affiliations

Application of the single-channel, single-energy AA/PWA method to $K^{+} Λ$ photoproduction

Search for the $α$ + core structure in the ground state bands of $22 \leq Z \leq 42$ even-even nuclei