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

TL;DR

This study investigates the existence of a $^7$H resonant state as a five-body system, finding no narrow low-energy resonance but identifying a broad structure at about 9 MeV, indicating a very broad $^7$H ground state.

Contribution

The paper introduces a new five-body model for $^7$H and uses advanced computational methods to analyze its resonance structure, providing insights into its possible ground state.

Findings

No narrow low-energy $^7$H resonance was found.

A broad resonance at approximately 9 MeV was identified.

Broad structures for $^6$H ground state were also observed.

Abstract

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 Schr\"{o}dinger 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 $J^{\pi}=2^-$.