An international research team has found evidence of the existence of an exotic atomic nucleus state in an experiment at the GSI/FAIR research center in Darmstadt. Although such a state has long been predicted theoretically, it has never been observed before. The system consists of an atomic nucleus of the carbon isotope ¹¹C and an η′ meson (etaprime meson) — a short-lived particle composed of a quark and an antiquark. This system is bound exclusively by the strong interaction, i.e., the force…