<i>Ab initio</i> Gamow in-medium similarity renormalization group with resonance and continuum

Abstract

We have developed a novel ab initio Gamow in-medium similarity renormalization group (Gamow IMSRG) in the complex-energy Berggren framework. The advanced Gamow IMSRG is capable of describing the resonance and nonresonant continuum properties of weakly bound and unbound nuclear many-body systems. As test grounds, carbon and oxygen isotopes have been calculated with chiral two- and three-nucleon forces from the effective field theory. Resonant states observed in the neutron-dripline $^{24}\mathrm{O}$ are well reproduced. The halo structure of the known heaviest Borromean nucleus $^{22}\mathrm{C}$ is clearly seen by calculating the density distribution in which the continuum $s$ channel plays a crucial role. Furthermore, we predict low-lying resonant excited states in $^{22}\mathrm{C}$. The Gamow IMSRG provides tractable ab initio calculations of weakly bound and unbound open quantum systems.