Absence of a shell closure in $^{140}$Sn

Abstract

There are conflicting theoretical results about the presence of a shell closure in the neutron-rich nucleus $^{140}$Sn. We address this controversy by performing ab initio computations, using a nuclear interaction from chiral effective field theory that accurately reproduced and predicted low-lying states in doubly magic nuclei. We verify that this interaction accurately reproduces low-lying states in $^{133}$Sn. We assume that $^{140}$Sn exhibits a closed $7/2^-$ neutron subshell beyond $^{132}$Sn and compute its first excited $2^+$ state. The resulting energy is small and this contradicts the assumption.