Five-body resonances of 8He using the complex scaling method

TL;DR

This paper investigates the five-body resonances of 8He using the complex scaling method, predicting a new 0+_2 state and analyzing its structure and decay processes.

Contribution

It introduces a five-body cluster model with complex scaling to study 8He resonances, predicting a new 0+_2 state and detailing its structure and decay pathways.

Findings

Predicted a 0+_2 resonance at 6.3 MeV with a 3.2 MeV width.

Found the 0+_2 state mainly has a (p_{3/2})^2(p_{1/2})^2 configuration.

Revealed the sequential breakup process from 8He to 7He+n to 6He+n+n.

Abstract

The 0+ states of 8He are studied in a five-body 4He+n+n+n+n cluster model. Many-body resonances are treated on the correct boundary condition as Gamow states using the complex scaling method. The 0+_2 state of 8He is predicted as a five-body resonance in the excitation energy of 6.3 MeV with a width of 3.2 MeV, which mainly has a (p_{3/2})^2(p_{1/2})^2 configuration. In this state, number of the 0+ neuron pair shows almost two, which is different from the ground state having a large amount of the 2+ pair component. The monopole transition of 8He from the ground state into the five-body unbound states is also evaluated. It is found that the 7He+n component mostly exhausts the strength, while the 0+_2 contribution is negligible. The final states are dominated by 6He+n+n, not 4He+n+n+n+n. The results indicate the sequential breakup process of 8He to 7He+n to 6He+n+n by the monopole excitation.