Re-evaluation of log ft Values and β-Decay Modes of fp-Shell Nuclei

Abstract

In this study, we investigate the \(\beta \)-decay properties of proton-rich nuclei with atomic numbers Z = 21–30 using the proton-neutron quasiparticle random phase approximation (pn-QRPA) model. Our analysis includes Gamow–Teller (GT) strength distributions, half-lives, log \(\textit{ft}\) values, and stellar weak interaction rates under terrestrial and stellar conditions. A fully microscopic pn-QRPA framework was employed to carry out the calculations. The calculated GT strength distributions show good agreement with experimental data. The predicted \(\beta \)-decay half-lives reproduce the measured values for more than \(90\%\) of the nuclei within a factor of 10. The computed log \(\textit{ft}\) values show decent agreement and are reproduced within a factor of 2 compared to the measured data. We computed the stellar (\(\beta ^{+}\)+ EC) decay rates and compared them with previous calculations such as large-scale shell model (LSSM) and the independent particle model (IPM). In high density regime, as the core temperature increased, our pn-QRPA based rates were found to up an order of magnitude smaller than those predicted by LSSM and IPM rates. These results provide crucial nuclear physics inputs for modeling the rapid-proton capture (rp) nucleosynthesis process, particularly in post-core silicon burning phases of massive star evolution. The present study enhances the reliability of the pn-QRPA approach in predicted \(\beta \)-decay properties and highlights its importance in astrophysical nucleosynthesis simulations. In our pn-QRPA calculations, no explicit quenching factor was used.