^6Li as a Three-Body System in the (p, ^3He ) Reaction at Astrophysical Energies

Several astrophysical processes are governed by the occurrence of nuclear reactions involving light nuclei at energies below the Coulomb barrier. Among other effects, their understanding is challenged by the appearance of clustered structures in the ground-state configuration of some of these nuclei, which may have a significant impact on the reaction cross section. In this contribution, we focus on the ^6Li ( p , ^3He ) ^4He reaction, to probe the role of clustered configurations of ^6Li . In particular, we consider a three-body ab-initio calculation, based on the hyperspherical harmonics (HH) method, of the ^6Li wave function (WF), together with a more phenomenological three-body model. We observe that the HH WF entails a degree of clustering much larger than obtained from the phenomenological WFs. However, the corresponding reaction cross section, evaluated as a direct two-nucleon transfer in distorted-wave Born approximation, still follows the scaling with the clustering strength already pointed out in a previous work (Perrotta et al. in Phys Rev C 108(4), 044614, 2023, https://doi.org/10.1103/PhysRevC.108.044614 ) and exhibits an energy trend very similar to that obtained with realistic phenomenological WFs. This opens up interesting perspectives towards constraining the extent of clustering effects in ground state configurations from the comparison to cross-section experimental data.