$^7$H ground state as a $^3$H+4n resonance

International audienceWe have investigated the possible existence of a 7H resonant state, considered as a five-body system consisting of a 3H core with four valence neutrons. To this aim, an effective n-3H potential is constructed in order to reproduce the low energy elastic neutron scattering on 3H phase shifts and the 5H resonant ground state in terms of 3H-n-n system. The variational Gaussian Expansion Method is used to solve the 5-body Schrödinger equation, while the resonant state parameters were estimated by means of the stabilization method. We have not found any sign of a narrow low energy resonance in the vicinity of 3H+4n threshold. However, we have identified a very broad structure at ER≈9 MeV above this threshold, which corresponds to the 7H J=π1/2+ ground state. In the vicinity of this state, we have also identified a broad structure corresponding to the ground state of 6H isotope with quantum numbers Jπ=2−