Ab initio investigations of A=8 nuclei: $\alpha{-}\alpha$ scattering, deformation in $^8$He, radiative capture of protons on $^7$Be and $^7$Li and the X17 boson

TL;DR

This paper uses the No-Core Shell Model with Continuum to study light nuclei, testing chiral nuclear forces against experimental data, and investigates phenomena including alpha-alpha scattering, radiative capture, and the X17 boson.

Contribution

It applies the NCSMC to various light nuclear systems, providing insights into nuclear structure, reactions, and potential new physics like the X17 boson, with a focus on chiral interactions.

Findings

Successful description of alpha-alpha scattering and $^8$Be structure.

Analysis of radiative capture processes relevant to solar physics.

Investigation of the exotic $^8$He nucleus and deformation phenomena.

Abstract

We apply the No-Core Shell Model with Continuum (NCSMC) that is capable of describing both bound and unbound states in light nuclei in a unified way with chiral two- and three-nucleon interactions as the only input. The NCSMC can predict structure and dynamics of light nuclei and, by comparing to available experimental data, test the quality of chiral nuclear forces. We discuss applications of NCSMC to the $\alpha{-}\alpha$ scattering and the structure of $^8$Be, the p+$^7$Be and p+$^7$Li radiative capture and the production of the hypothetical X17 boson claimed in ATOMKI experiments. The $^7$Be(p,$\gamma$)$^8$B reaction plays a role in Solar nucleosynthesis and Solar neutrino physics and has been subject of numerous experimental investigations. We also highlight our investigation of the neutron rich exotic $^8$He that has been recently studied experimentally at TRIUMF with an unexpected deformation reported.