Speaker
Description
Nuclei in the vicinity of driplines have been receiving a lot of attention in nuclear structure studies. Continuum coupling plays a pivotal role in accurately describing weakly bound and unbound phenomena in these nuclei. To calculate observables of the nuclei as open quantum systems, we have developed valence-space effective operators in the complex-energy Berggren basis using many-body perturbation theory. We focus on the Gamow-Teller $\beta$ decay in the $sd$ shell. The two- plus three-nucleon force from the chiral effective field theory, named EM1.8/2.0, has been used. The Gamow shell model which takes the continuum coupling into account can properly reproduce experimental observations of weakly bound and unbound states. The $\beta$-decay isospin asymmetry between the dripline nucleus $^{22}$Si and its mirror partner $^{22}$O is reproduced, in which the $s_{1/2}$ continuum plays a key role. Significant Thomas-Ehrman shift is seen through mirror energy differences between the mirror daughters $^{22}$Al and $^{22}$F, in which the continuum effect plays an important role.
