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### Effects of beyond mean field approximation and tensor forces on Gamow-Teller and β decay of magic nuclei

05/16

**2024**Seminar-
*Title*Effects of beyond mean field approximation and tensor forces on Gamow-Teller and β decay of magic nuclei -
*Speaker*Hiroyuki Sagawa (University of Aizu) -
*Date*14:00 May 16, 2024 -
*Venue*322

*Abstract*

The self-consistent Hartree-Fock (HF)+subtracted second random phase approximation (SSRPA) calculations based on the Skyrme energy density functions (EDFs) are performed for the Gamow-Teller (GT) excitations of four closed shell nuclei 48Ca, 90Zr, 132Sn, and 208Pb to study the systematic trend of SSRPA on the description of GT strength distributions with respect to the excitation energy and the width [1]. We apply also the SSRPA model including tensor force to the decay half-lives in magic and semi-magic nuclei, 34Si, 68, 78Ni and 132Sn with Skyrme EDFs. The inclusion of the two particle-two hole (2p-2h) configurations in the SSRPA model shifts low-lying GT states downwards. It leads to an increase of the β decay phase space, which ensures the half-lives of the four nuclei are finite and reduces the β decay half-lives dramatically. The effect of tensor interaction on the β decay half-life in 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 [2]. We further study magnetic dipole (M1) transitions of magic nuclei to disentangle the role of triplet-even and triplet-odd tensor forces in the spin-isospin excitations [3].

**References**

[1] M. J. Yang, C. L. Bai, H. Sagawa, and H. Q. Zhang, Phys. Rev. C 106, 014319 (2022).

[2] M. J. Yang, H. Sagawa, C. L. Bai, and H. Q. Zhang, Phys. Rev. C 107, 014325 (2023).

[3] M. J. Yang, H. Sagawa, C. L. Bai, and H. Q. Zhang, Phys. Rev. C in press (2024).

**Biography**

Prof. Hiroyuki Sagawa is a theoretical physicist specializing in collective motion in nuclei, spin-isospin excitations, exotic nuclei, charge symmetry breaking in nuclei and hypernuclei. He obtained his Ph.D. in Physics from Tohoku University in 1975, focusing on nuclear theory. He has worked at the University of Tokyo,Utsunomiya University, Niels Bohr Institute, Universié de Paris-Sud, National Institute of Nuclear and High Energy Institute (NIKHEF) at Amsterdam, Michigan State University, and the University of Aizu. Now, he is a Senior Visiting Scientist at RIKEN Nishina Center and a Professor Emeritus at the University of Aizu.

**Inviter**

Shan-Gui Zhou