Speaker
Description
The light nuclei attract the interest of the nuclear physics community for decades, however, we are still far away from their complete understanding. A notable example is the $^4$He, a simple and very stable nucleus constituted by two protons and two neutrons. Until a description of nuclei directly from the fundamental theory of quarks and gluons becomes computationally feasible, an effective way to proceed is to assume composite particles like protons and neutrons and the interactions among them as the basic degrees of freedom. Successful reparametrizations and models of these interactions have been developed in the last decades, which are able to accurately reproduce all the known data of proton and neutron scatterings, as well as the properties of few-body nuclear systems. However, recent electron scattering results focusing on the first excited resonant state of $^4$He nucleus, reveal a puzzling situation suggesting potential gaps in our understanding of nuclear phenomenology. Into this context, we performed new measurements of the $^4$He(0$^+_2$) resonance by $^4$He + $^4$He scattering at the MAGNEX facility of INFN – Laboratori Nazionali del Sud, featuring data of unprecedented sensitivity and state-of-art analyses of the spectral line shape together with a phenomenological reaction modeling based on a two coupled-channel system that incorporates the same ab-initio nuclear densities employed in electron-scattering studies.