Nuclear Theory·nucl-th

Friday·January 17, 2025

8 papers—5 primary·3 cross-listed

01
[Submitted on 16 Jan 2025]
Robust ab initio predictions for dimensionless ratios of E2 and radius observables. II. Estimation of E2 transition strengths by calibration to the charge radius
Mark A. Caprio · Patrick J. Fasano · Pieter Maris
Converged results for E2 observables are notoriously challenging to obtain in ab initio no-core configuration interaction (NCCI) approaches. Matrix elements of the E2 operator are sensitive to the large-distance tails of the nuclear wave function, which converge slowly in an oscillator basis expansion. Similar convergence challenges beset ab initio prediction of the nuclear charge radius. However, we exploit systematic correlations between the calculated E2 and radius observables to yield meaningful predictions for relations among these observables. In particular, we examine ab initio predictions for dimensionless ratios of the form B(E2)/(e^2r^4), for nuclei throughout the p shell. Meaningful predictions for E2 transition strengths may then be made by calibrating to the ground-state charge radius, if experimentally known.
Comments:
18 pages, 11 figures. arXiv admin note: text overlap with arXiv:2409.03926
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2501.09228 [pdf]
PRC(2025)·6 citations
02
[Submitted on 16 Jan 2025]
Order-by-order uncertainties of nucleon-nucleon Wolfenstein amplitudes in chiral effective field theory
B. McClung🇺🇸 · Ch. Elster🇺🇸 · D. R. Phillips🇺🇸
Quantum mechanical invariance principles dictate the most general operator structure that can be present in the nucleon-nucleon (NN) interaction. Five independent operators appear in the on-shell NN amplitude together with five corresponding coefficient functions. The usual choice for these coefficient functions is known as the NN Wolfenstein amplitudes. We analyze the order-by-order convergence of each of the five NN Wolfenstein amplitudes predicted by a semi-local coordinate space potential implementation of chiral effective field theory ( $χ$ EFT). We do this at laboratory kinetic energies between 25 and 200 MeV for both neutron-proton and proton-proton scattering. Our analysis uses the Gaussian-Process methods developed by the BUQEYE collaboration to describe the contributions of each $χ$ EFT order, and so yields truncation uncertainties for each Wolfenstein amplitude that are correlated across scattering angles. We combine information on the size of different orders in the EFT to infer the $χ$ EFT breakdown scale for each amplitude, finding, on average, $Λ_{b}$ between 750 and 800 MeV. With this choice of $Λ_{b}$ , the EFT truncation uncertainties cover both higher-order results and empirical Wolfenstein amplitudes well for all orders other than the leading order.
Comments:
16 pages, 22 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2501.09231 [pdf]
PRC(2025)·2 citations
03
[Submitted on 16 Jan 2025]
Visualization of quantum interferences in heavy-ion elastic scattering
Kyoungsu Heo · K. Hagino
We investigate various interference effects in elastic scattering of the $α +^{40} Ca$ system at $E_{lab} = 29$ MeV. To this end, we use an optical potential model and decompose the scattering amplitude into four components, that is, the near-side and the far-side components, each of which is further decomposed into the barrier-wave and the internal-wave components. Each component contributes distinctively to the angular distributions, revealing unique quantum interference patterns. We apply the Fourier transform technique to visualize these interference effects. By analyzing the images at specific scattering angles, we identify the positions and intensities of peaks corresponding to each interference component. This analysis offers insight into structural features of the angular distribution which are not apparent from the differential cross sections alone.
Comments:
6 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2501.09348 [pdf]
PRC(2025)·2 citations
04
[Submitted on 16 Jan 2025]
The $α$ condensate states of atomic nuclei $^{12} C$ , $^{16} O$ and $^{20} N e$ in an analytical solvable model
Bao-Xi Sun
The $α$ condensation in the $^{12} C$ , $^{16} O$ and $^{20} N e$ nuclei is investigated within an analytical solvable model. It is found that the calculated ratio of the ground state energies of the Hoyle state of $^{12} C$ and the Hoyle-like state of $^{16} O$ is consistent with that of the experimental values. Along this clue, the ground state energy of $^{20} N e$ is obtained to be 1MeV approximately, which is far less than the experimental value of 3MeV. Additionally, the root-mean-square radii of these nuclei are also calculated, and all of them lies around 9fm, which is different from the result calculated with the Tohsaki-Horiuchi-Schuck-Ropke(THSR) wave function. Since the root-mean-square radius is relevant to the ground state energy of the $α$ condensate nucleus, the root-mean-square radii of $^{16} O$ and $^{20} N e$ are also calculated with the ground state energies used in the THRS wave function. As a result, the root-mean-square radii of $^{16} O$ and $^{20} N e$ reduced to 5fm, and it is similar to the result obtained with the THRS wave function. The calculation result manifests that the root-mean-square radius of $α$ condensate nuclei decreases with the energy increasing.
Comments:
12 pages, 1 table
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2501.09406 [pdf]
0 citations
05
[Submitted on 16 Jan 2025]
Exploring the possible two-proton radioactivity of $^{38, 39}$ Ti
B. Huang · F. P. Bai · D. Q. Fang · S. M. Wang
Two-proton (2 $p$ ) radioactivity represents a rare decay mode that has been experimentally observed only in a selected few nuclei. The exploration of 2 $p$ emission is crucial for elucidating the structure, mass, and nucleon-nucleon interactions within exotic proton-rich nuclei. $^{39}$ Ti has long been postulated as a potential candidate for 2 $p$ emission; however, experimental investigations have yet to confirm its 2 $p$ decay. To provide more accurate information for further studies, we utilize the Gamow shell model (GSM) and the Gamow coupled channel (GCC) method to analyze the prospective 2 $p$ radioactivity of isotopes $^{38, 39}$ Ti. Our calculations suggest that $^{39}$ Ti is indeed a viable candidate for 2 $p$ emission. Notably, the estimated partial 2 $p$ decay width for $^{39}$ Ti, predicted from the three-body GCC method, suggests that its 2 $p$ decay could rival its $β$ decay in likelihood, although this is highly dependent on the specific 2 $p$ decay energy. Additionally, our analysis indicates a propensity for pairing between the valence protons in $^{39}$ Ti. A similar investigative approach reveals that $^{38}$ Ti exhibits a higher 2 $p$ decay energy and a broader decay width than $^{39}$ Ti, positioning it as a more promising candidate for 2 $p$ decay.
Comments:
9 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2501.09542 [pdf]
PLB(2025)·2 citations

Affiliations

first authorsco-authorsvia INSPIRE

Robust ab initio predictions for dimensionless ratios of E2 and radius observables. II. Estimation of E2 transition strengths by calibration to the charge radius

Order-by-order uncertainties of nucleon-nucleon Wolfenstein amplitudes in chiral effective field theory

Visualization of quantum interferences in heavy-ion elastic scattering

The α condensate states of atomic nuclei 12C, 16O and 20Ne in an analytical solvable model

Exploring the possible two-proton radioactivity of 38,39Ti

Affiliations

The $α$ condensate states of atomic nuclei $^{12} C$ , $^{16} O$ and $^{20} N e$ in an analytical solvable model

Exploring the possible two-proton radioactivity of $^{38, 39}$ Ti