Exploring exotic reactions with a few-body model

Theoretical models capable of describing nuclei far from stability are essential in the radioactive-beam era. At the dripline, weak binding and strong coupling between bound states and the continuum give rise to cluster phenomena, including the emergence of halo nuclei. The difficulty of constructing experiments that can extract detailed information from these extremely short-lived isotopes means that they must be studied through reactions, wherein a theoretical model is used to extract physical information from the data. I discuss two-neutron halo nuclei, for which a three-body model is required. Traditionally, structure information, such as shell-model level energies, has been incorporated through the two-body interactions used in the model.
I present results obtained with a new code that exploits modern computer architectures to reduce computation time, enabling comprehensive uncertainty quantification. I use the hyperspherical harmonic basis and the calculable R-matrix to treat bound and scattering states on the same footing. I perform a Bayesian calibration to propagate uncertainties in the two-body structure to the three-body level. I examine the impact of these uncertainties on the ground state and dipole strength of two-neutron halos, focusing on the interesting example of 22C. The dipole strength function exhibits universal behaviour in its dependence on binding energy, consistent with Halo EFT. However, the underlying structure also reflects shell effects. Finally, I outline possible extensions of this model and other systems to which it can be readily applied.