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

We have investigated the possible existence of a ${}^7$H resonant state, considered as a five-body system consisting of a ${}^3$H core with four valence neutrons. To this aim, an effective n-${}^3$H potential is constructed in order to reproduce the low energy elastic neutron scattering on ${}^3$H phase shifts and the ${}^5$H resonant ground state in terms of ${}^3$H-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 ${}^3$H+4n threshold. However, we have identified a very broad structure at $E_R\approx 9$ MeV above this threshold, which corresponds to the ${}^7$H J${}^{\pi }$=1/2${}^{+}$ ground state. In the vicinity of this state, we have also identified a broad structure corresponding to the ground state of ${}^6$H isotope with quantum numbers $J^{\pi }=2^{-}$.