Ponente
Descripción
If pn pairing in the T=0 channel exists, one would expect a very collective $0^+ \rightarrow 1^+$ Gamow-Teller (GT) transition in the beta decay of a Z=N+2 nucleus into its N=Z counterpart [1], similar in strength to the super-allowed Fermi transition connecting the $0^+$ isobaric analog states. In a study performed at RIBF looking for these effects in the region around $A \sim 70$, we have found an enhancement of the GT strength in the beta decay of $^{70}$Kr into $^{70}$Br [2]. Even though the deduced strength does not represent a clear-cut indication of T=0 pn pairing in this case, a possible enhancement of T=0 pn pairing effects has been predicted in the past when moving to systems heavier than mass A=70 [3].
Closely related, our study on the beta decay of $^{70}$Kr [2] showed clearly that even though the SU(4) symmetry is expected to be broken due to the increasing role of the spin-orbit interaction in heavy nuclei, the pseudo SU(4) symmetry is partially recovered for this system, when compared with lighter Z=N+2 decays, indicating also a change in the trend around A=70 [4].
In collaboration with the BigRIPS team [5], a feasibility assessment is presently being performed about the possibility to reach heavier Z=N+2 systems for study. The goal is to further test the validity of the pseudo SU(4) symmetry for systems beyond A=70. Depending on the feasibility, we propose to study the best reachable heavier Z=N+2 decay in order to clarify further this question.
[1] A.L. Goodman, Phys. Rev. C 60 (1999) 014311; S. Frauendorf, A.O. Macchiavelli, Prog. Part. Nucl. Phys. 78 (2014) 24; F. Iachello, Proc. Int. Conf. on Perspectives for the IBM, Padova, Italy, 1994, p.1.; F. Iachello, Yale University, preprint YCTP-N13-88.; P. Halse, B. R. Barrett, Ann. Phys. (N. Y.) 192 (1989) 204.
[2] A. Vitéz-Sveiczer et al., Phys. Lett. B, 830 (2022) 396.
[3] J. Jänecke, T. W. O’Donnell, Phys. Lett. B 605 (2005) 87.
[4] P. Van Isacker et al., Symmetry 15 (2023) 2001.
[5] N. Fukuda, private communication.
