Complex-energy eigenvector continuation for nuclear many-body broad resonances

TL;DR

This paper extends the eigenvector continuation method into complex-energy space to efficiently analyze broad nuclear resonances, reducing computational complexity while maintaining accuracy.

Contribution

The paper introduces a novel complex-energy eigenvector continuation approach for broad nuclear resonances, enabling accurate predictions with limited input data.

Findings

Successfully applied to $^4$H, $^4n$, $^6$He, and $^7$He resonances

Achieved accurate resonance solutions using few input states

Reduced computational complexity in nuclear resonance calculations

Abstract

Broad resonances are a unique phenomenon in nuclear many-body systems. Theoretical studies usually involve the continuum degree of freedom, which drastically increases the model space of calculations, and may lead to non-convergence or instability of computations. In this paper, we present the extension of the eigenvector continuation (EC) method to the complex-energy space to treat the broad resonances of open quantum systems of nuclei. EC provides an efficient method to predict the solution of a large-space many-body problem within a small subspace. Using only a few bound and narrow resonance solutions as input in EC, we can obtain the solution of a broad resonance. We have applied the complex-energy EC to the broad resonances of $^4$H, four-neutron $^4n$, $^6$He and $^7$He systems.