nucl-th digest · Nov 11, 2024

Configuration interaction relativistic Hartree-Fock model

The configuration interaction relativistic Hartree-Fock (CI-RHF) model is developed in this work. Compared to the conventional configuration interaction shell model (CISM), the CI-RHF model can be applied to study the structural properties of a wide range of nuclei without readjusting any parameters, as the effective Hamiltonian for different model space can be deduced consistently from a universal density-dependent Lagrangian based on the Hartree-Fock single-particle basis. The convergence of intermediate-state excitations has been examined in evaluating the effective interactions, and the core-polarization effects are illustrated, by using

^{18}

O as an example. Employing the CI-RHF model, both the bulk properties and low-lying spectra of even-even nuclei

^{18 \sim 28}

Ne have been well reproduced with the model space restricted to the

s d

shell. Studies of the isotopic evolution concerning charge radii and low-lying spectra highlight the shell closure at

N = 14

for neon isotopes. Furthermore, the cross-shell calculations extending from the

s d

p f

shell successfully reproduced the low-lying spectra of

^{30}

Ne and

^{32}

Ne. Notably, remarkably low excitation energies

E (2_{1}^{+})

^{30}

Ne suggest the disappearance of the conventional magicity

N = 20

Comments:: 6 figures
Subjects:: Nuclear Theory (nucl-th)
arXiv:: 2411.05370 [pdf]

CPC(2025)·7 citations

[Submitted on 8 Nov 2024]

Radiative and exchange corrections for two-neutrino double-beta decay

Ovidiu Niţescu🇸🇰 · Fedor Šimkovic🇸🇰

We investigate the impact of radiative and atomic exchange corrections in the two-neutrino double-beta ( $2 ν β β$ )-decay of $^{100}$ Mo. In the calculation of the exchange correction, the electron wave functions are obtained from a modified Dirac-Hartree-Fock-Slater self-consistent framework that ensures orthogonality between continuum and bound states. The atomic exchange correction causes a steep increase in the low-energy region of the single-electron spectrum, consistent with previous studies on $β$ -decay, while the radiative correction primarily accounts for a 5\% increase in the decay rate of $^{100}$ Mo. When combined, the radiative and exchange effects cause a leftward shift of approximately 10 keV in the maximum of the summed electron spectrum. This shift may impact current constraints on parameters governing potential new physics scenarios in $2 ν β β$ -decay. The exchange and radiative corrections are introduced on top of our previous description of $2 ν β β$ -decay, where we used a Taylor expansion for the lepton energy parameters within the nuclear matrix elements denominators. This approach results in multiple components for each observable, controlled by the measurable $ξ_{31}$ and $ξ_{51}$ parameters. We explore the effects of different $ξ_{31}$ and $ξ_{51}$ values, including their experimental measurements, on the total corrected spectra. These refined theoretical predictions can serve as precise inputs for double-beta decay experiments investigating standard and new physics scenarios within $2 ν β β$ -decay.

Comments:: 12 pages, 5 figures
Subjects:: Nuclear Theory (nucl-th); High Energy Physics — Theory (hep-th)
arXiv:: 2411.05405 [pdf]

PRC(2025)·12 citations

Monday·November 11, 2024

Configuration interaction relativistic Hartree-Fock model

Radiative and exchange corrections for two-neutrino double-beta decay

Affiliations