Does tetraneutron theoretically exist?

At RIKEN RI Beam Factory (RIBF), a candidate for tetraneutron was reported. However, from the reported energy, it is impossible to rule out either possibility that this nucleus is in a constrained state or in a resonant state. It is pointed out that T=3/2 3 nucleon force contributes to the binding energy of this nucleus. However, there is no knowledge as to how much this 3 nucleon force contributes to its binding energy. In theory, it is necessary to answer the questions whether one can reproduce the experimental values using realistic nuclear forces and T=3/2 3 nucleon force, and how much T=3/2 3 nucleon force contributes to the binding energy of this nucleus. This study investigated this theoretical problem using the Gaussian expansion method based on infinitesimal displacement Gauss-Lobe basis functions. As long as AV8' realistic two nucleon force and phenomenological T=3/2 3 nucleon force are used, it is very difficult to reproduce the current experimental values. However, although phenomenological T=3/2 three body force is used here, one need to compare it with the experimental value by theoretical calculation of the resonance state using elaborate three body force. Furthermore, a tetraneutron exploration experiment in the new RIBF was conducted and the results are being analyzed, so its results are waited. (A.O.)