Effects of Beyond Mean Field and Tensor Force on Gamow–Teller and \(\beta \) Decay of Magic Nuclei
Hiroyuki Sagawa, M.J. Yang, C. L. Bai · Acta Physica Polonica B Proceedings Supplement · 2025
We explore extensively new, and also long-standing, but still unsolved, nuclear structure problems by using beyond-mean-field model, Subtracted Second Random Phase Approximation (SSRPA). Firstly, the similarity between the subtraction method of SSRPA and Lee–Suzuki similarity transformation is pointed out to get the physical background of the SSRPA model. Secondly, we study the spin–isospin and electric excitations including the couplings to two-particle–two-hole states and the tensor correlations. Our results give a new insight into the quenching the of Gamow–Teller (GT) sum rule strengths without introducing any adjustable parameters in the self-consistent microscopic calculations. We further apply the SSRPA model to the \(\beta \) decay half-lives of four semi-magic and magic nuclei, \(^{34}\rm Si\), \(^{68,78}\rm Ni\), and \(^{132}\rm Sn\). The inclusion of the two-particle–two-hole (\(2p\)–\(2h\)) configurations shifts low-lying GT states downwards. It leads to an increase of the \(\beta \) decay phase space, which ensures the half-lives of the four nuclei are finite and reduces the \(\beta \) decay half-lives dramatically. The effect of tensor interaction on the \(\beta \) decay half-life in the SSRPA model is also pointed out to change largely the half-lives by about one to two orders of magnitude with respect to the ones obtained without tensor force. The magnetic dipole transitions are also studied in the SSRPA model. Abstract Published by the Jagiellonian University 2025 authors