Efimov effect in the nuclear halo ${}^{14}$Be nucleus

The Efimov effect in the halo nucleus ${}^{14}$Be, considered as a three-body (${n-n-}^{12}$Be) system, is studied employing separable potential for the binary systems. Assuming a possibility for the existence of a low lying $s$-orbital state for the halo neutrons with ${}^{12}$Be as core, we investigate its effect on the possibility of occurrence of the Efimov states by computing the three-body integral equations. A virtual state of 2 to 4 keV for the $n$-${}^{12}$Be binary system predicts not only the ground state energy for ${}^{14}$Be, which is in reasonable agreement with the experimental value, but also shows excited states close to about zero binding energy for the halo neutrons.