Nuclear Theory·nucl-th

Tuesday·December 13, 2022

16 papers—8 primary·8 cross-listed

01
[Submitted on 9 Dec 2022]
Weak decay of halo nuclei
Wael Elkamhawy🇩🇪 · Hans-Werner Hammer🇩🇪 · Lucas Platter🇺🇸
We investigate the weak decay of one-neutron halo nuclei into the proton-core continuum, i.e., beta-delayed proton emission from the halo nucleus using a cluster effective field theory for halo nuclei. On the one hand, we calculate the direct decay into the continuum. On the other hand, we consider the case of resonant final state interactions between the proton and the core. We present our formalism and discuss the application to the decay of $^{11}$ Be in detail. Moreover, we compare to recent experimental results for the branching ratio and resonance parameters. As another example, we consider the case of $^{19}$ C and predict the branching ratio for beta-delayed proton emission.
Comments:
20 pages, 7 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2212.05087 [pdf]
PRC(2023)·2 citations
02
[Submitted on 9 Dec 2022]
Nuclear matter from the ladder resummation in terms of the experimental nucleon-nucleon scattering amplitudes
J. M. Alarcón🇪🇸 · J. A. Oller🇪🇸
Infinite nuclear matter is studied by resuming the series of ladder diagrams based on the results developed by us in Ann. Phys. 437, 168741 (2022). The master formula for the energy density is explicitly solved for the case of contact interactions, within a pionless description of the nucleon-nucleon interactions. Renormalized results are obtained which are directly expressed in terms of the nucleon-nucleon phase shifts and mixing angles in partial-wave amplitudes up to an including $G$ waves, with convergence reached under the inclusion of higher partial waves. The energy per particle, density and sound velocity resulting from the ladder series are given for symmetric and neutron matter. This resummation of the ladder diagrams provides a rigorous result that may be used as low-density reference for other parameterizations of $E ˉ$ for higher densities.
Comments:
29 pages, 9 figures
Subjects:
Nuclear Theory (nucl-th); Quantum Gases (cond-mat.quant-gas); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2212.05092 [pdf]
PRC(2023)·11 citations
03
[Submitted on 11 Dec 2022]
How and How Much is $g_{A}$ {\it Fundamentally} Quenched in Nuclei?
Mannque Rho🇫🇷
The superallowed Gamow-Teller transition in the doubly-magic-shell nucleus $^{100}$ Sn and the high resolution spectral shape analysis in the fourth-forbidden nonunique transition in $^{115}$ In indicate as much as $\sim 40%$ {\it fundamental} quenching in the axial-current coupling constant $g_{A}$ in nuclei. This can be attributed to an effect of the trace anomaly in QCD "emerging" in nuclear medium. If confirmed, this would signal a major revamping to do in nuclear interactions consistent with chiral-scale symmetry in nuclear medium and a big impact on $0 ν$ and $ν ν$ double $β$ decays for BSM. I present an argument that such a big anomaly-induced quenching is incompatible with how hidden scale symmetry manifests in nuclear medium, A possible means to resolve this issue is discussed in terms of hidden scale symmetry permeating in baryonic matter from normal nuclear matter to massive compact-star matter.
Comments:
6 pages, no figures, a few typos corrected
Subjects:
Nuclear Theory (nucl-th); High Energy Physics — Phenomenology (hep-ph)
arXiv:
2212.05558 [pdf]
1 citation
04
[Submitted on 12 Dec 2022]
Spectral function of the $η^{'}$ meson in nuclear medium based on phenomenological models
Shuntaro Sakai🇯🇵 · Daisuke Jido🇯🇵
The in-medium modification of the spectral function of the $η^{'}$ meson with and without the spatial momentum is studied with the $T ρ$ approximation by employing two phenomenological models for the $η^{'} N$ scattering; one is called coupled channels model and the other the $N (1895)$ -dominance model. In the former model, the $η^{'} N$ scattering amplitude is calculated in the unitarized coupled-channel approach involving the $η^{'} N$ channel, while in the latter model the $η^{'} N$ scattering process is dominated by the $N (1895)$ resonance with the spin and parity $J^{P} = 1/ 2^{-}$ . In the \com{coupled channels model}, one single peak of the in-medium $η^{'}$ mode appears in the spectral function and the peak position shifts to higher energies along with the increase of the nuclear density reflecting the repulsive $η^{'} N$ scattering length of the unitarized coupled-channel amplitude. On the other hand, two branches related to the $η^{'}$ and $N (1895)$ -hole modes appear in the $N (1895)$ -dominance model. In both models, the shift of the peak position and the width in the spectral function are a few tens of MeV at the normal nuclear density for the $η^{'}$ meson at rest in the nuclear medium. Once the spatial momentum is turned on, the peak positions in the spectral function approach the energies without the nuclear medium effect. Particularly, in the $N (1895)$ -dominance model, the peak strength of the $N (1895)$ -hole mode gets smaller with the finite momentum and the spectral function comes to have one single peak.
Comments:
16 pages, 14 figures. Typos are corrected
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2212.05655 [pdf]
PRC(2023)·6 citations
05
[Submitted on 12 Dec 2022]
Possible neutron halo in triaxial nucleus 42Al
K. Y. Zhang · S. Q. Zhang · J. Meng
A microscopic self-consistent triaxial relativistic Hartree-Bogoliubov theory in continuum (TRHBc), which simultaneously takes into account the triaxiality and pairing correlations as well as continuum effects, is established and applied to explore the novel halo phenomenon in aluminum isotopes. The experimental proton drip line and the available data of neutron separation energies and charge radii are reproduced well without any free parameters. The neutron-richest odd-odd aluminum isotope observed so far, 42Al, is predicted to be triaxially deformed with beta=0.35 and gamma=42. Its one-neutron separation energy is predicted to be 0.68 MeV, in agreement with the AME2020, and the neutron rms radius is 3.94 fm, remarkably larger than the empirical value. The density distribution of the valance neutron, which extends much farther in space than the core, suggests a possible neutron halo in 42Al. The dominant components responsible for the spatial extension of the halo are revealed by the single-neutron orbitals around the Fermi energy. A novel phenomenon, the exchange of the intermediate and short axes between the triaxial core with beta=0.38 and gamma=50, and the triaxial halo with beta=0.79 and gamma=-23, is found. Future experiments to explore the halo phenomenon and the novel shape decoupling in 42Al are highly demanded.
Comments:
6 pages, 5 figures
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2212.05703 [pdf]
PRC(2023)·41 citations
06
[Submitted on 12 Dec 2022]
Islands of shape coexistence: theoretical predictions and experimental evidence
Andriana Martinou · Dennis Bonatsos · S.K. Peroulis · K.E. Karakatsanis · T.J. Mertzimekis · N. Minkov
Parameter-free theoretical predictions based on a dual shell mechanism within the proxy-SU(3) symmetry of atomic nuclei, as well as covariant density functional theory calculations using the DDME2 functional indicate that shape coexistence (SC) based on the particle-hole excitation mechanism cannot occur everywhere on the nuclear chart, but is restricted on islands lying within regions of 7-8, 17-20, 34-40, 59-70, 96-112, 146-168 protons or neutrons. Systematics of data for even-even nuclei possessing K=0 (beta) and K=2 (gamma) bands support the existence of these islands, on which shape coexistence appears whenever the K=0 bandhead 0_2^+ and the first excited state of the ground state band 2_1^+ lie close in energy, with nuclei characterized by 0_2^+ lying below the 2_1^+ found in the center of these islands. In addition a simple theoretical mechanism leading to multiple shape coexistence is briefly discussed.
Comments:
14 pages, 3 tables, 5 figures
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2212.05940 [pdf]
Symmetry(2023)·18 citations
07
[Submitted on 12 Dec 2022]
Interplay of longitudinal and transverse expansion in the kinetic dynamics of heavy-ion collisions
Piotr Bozek🇵🇱
The early dynamics in heavy-ion collisions involves a rapid, far from equilibrium evolution. This early pre-equilibrium stage of the dynamics can be modeled using kinetic equations. The effect of this pre-equilibrium stage on final observables derived from transverse momenta of emitted particles is small. The kinetic equations in the relaxation time approximation for a non-boost invariant system are solved. The asymmetry of the flow with respect to the reaction plane at different rapidities is found to be very sensitive to the degree of non-equilibrium in the evolution. This suggests that the rapidity odd directed flow could be studied to identify the occurrence of non-equilibrium effects and to estimate the asymmetry of the pressure between the longitudinal and transverse directions in the collision.
Comments:
discussion reviewed, typos corrected
Subjects:
Nuclear Theory (nucl-th)
arXiv:
2212.06018 [pdf]
PRC(2023)·7 citations
08
[Submitted on 12 Dec 2022]
Quantifying uncertainties due to optical potentials in one-neutron knockout reactions
Chloë Hebborn · T. R. Whitehead · Amy E. Lovell · Filomena M. Nunes
One-neutron knockout reactions have been widely used to extract information about the single-particle structure of nuclei from the valley of stability to the driplines. The interpretation of knockout data relies on reaction models, where the uncertainties are typically not accounted for. In this work we quantify uncertainties of optical potentials used in these reaction models and propagate them, for the first time, to knockout observables using a Bayesian analysis. We study two reactions in the present paper, the first of which involves a loosely-bound halo projectile, $^{11}$ Be, and the second a tightly-bound projectile, $^{12}$ C. We first quantify the parametric uncertainties associated with phenomenological optical potentials. Complementing to this approach, we also quantify the model uncertainties associated with the chiral forces that can be used to construct microscopic optical potentials. For the phenomenological study, we investigate the impact of the imaginary terms of the optical potential on the breakup and stripping components of the knockout cross sections as well as the impact of the angular range. For the $^{11}$ Be case, the theoretical uncertainty from the phenomenological method is on the order of the experiment uncertainty on the knockout observables; however, for the $^{12}$ C case, the theoretical uncertainty is significantly larger. The widths of the confidence intervals for the knockout observables obtained for the microscopic study and the phenomenological approach are of similar order of magnitude. Based on this work we conclude that structure information inferred from the ratio of the knockout cross sections, will carry a theoretical uncertainty of at least $20%$ for halo nuclei and at least $40%$ for tightly-bound nuclei.
Comments:
Accepted for publication in Phys. Rev. C, 13 pages (including 2 of appendices and 1 of reference), 5 figures, 2 tables
Subjects:
Nuclear Theory (nucl-th); Nuclear Experiment (nucl-ex)
arXiv:
2212.06056 [pdf]
PRC(2023)·14 citations

Affiliations

first authorsco-authorsvia INSPIRE