Clustering studies with the symmetry-adaptied no-core shell model

Recent advancements with experiments at rare isotope beams facilities and in ab initio nuclear modeling, combined with state-of-the-art high-performance computing, have opened up new domains of the nuclear chart for study and prediction. Ab initio nuclear approaches build upon inter-nucleon interactions typically derived in chiral effective field theory with no parameters to adjust within the nuclear medium. They enable predictions for a variety of nuclei and their complex cluster substructures that are key to understanding associated reactions and decay modes. One such approach is the ab initio symmetry-adapted no-core shell model (SA-NCSM), which has expanded the reach of practically exact methods to medium-mass open-shell nuclei, including both spherical and deformed nuclei, as well as stable and short-lived exotic isotopes. This is achieved by leveraging key symmetries known to govern nuclear dynamics. In this framework, I will address a long-standing challenge, namely, the emergence of clustering in light to medium-mass nuclei from the physics of two or three nucleons alone, probed in part by first ab-initio informed alpha knockout reactions. In this talk, I will discuss exotic clusterization and associated decay modes in newly observed mass-8 resonances using the invariant-mass technique. Specifically, this study finds a new prompt two-proton emitter as well as 3He+5Li substructures, identified with the aid of the SA-NCSM, of significance to ongoing searches for exotic resonances in the proximity of the drip lines. In addition, I will illustrate the critical need for accurate descriptions of alpha clustering, first, in 8B and 8Li along with their beta-decay product 8Be, to reliably compute higher-order corrections with unprecedented uncertainties for high-precision beta-decay experiments that probe physics beyond the standard model; and second, in neon isotopes, to provide reliable predictions of alpha partial widths and spectroscopic factors, with implications for novae and x-ray burst astrophysical simulations.