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

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 $7\mathrm{/}{2}^{-}$ neutron subshell beyond ${}^{132}$Sn and compute its first excited $2^{+}$ state. The resulting energy is small and this contradicts the assumption.