Light kaonic atoms as probes of fundamental interactions in strange systems

The strong interaction, described within the Standard Model of particle physics by quantum chromodynamics (QCD), plays a fundamental role in understanding the structure and the stability of matter. Despite significant advances, the low-energy QCD regime remains poorly understood due to its non-perturbative nature. Kaonic atoms, in which a negatively charged kaon is bound to a nucleus via electromagnetic interaction, offer a unique experimental tool to investigate the strong interactions in the strangeness sector. Their study provides key information on the antikaon–nucleon interaction at threshold energy, essential for refining the relative theoretical models. This work reviews the current status of kaonic atom research, highlighting recent experimental findings and their impact on our understanding of the strong interaction. We discuss the formation processes, the role of X-ray spectroscopy in probing strong-interaction effects, and the latest results from DA Φ NE and J-PARC experimental facilities. Future perspectives, including planned experiments aimed at further improving the precision of the measurements and the potentiality of also measuring the high-n transitions as precision probes for quantum electrodynamics (QED) with strangeness, are also reviewed.