Tribute to Toshimitsu Yamazaki (1934-2025): Quest for Exotic Hadronic Matter

In this talk I pay tribute to Toshimitsu Yamazaki who died earlier this year. Yamazaki’s leading contributions to Hadronic Physics, in particular to Strangeness Nuclear Physics in Japan and elsewhere, are well known. Two of the five Recurring Themes of his research, as listed in the Japan Academy site, are highlighted here: (i) Discovery of deeply bound pionic-atom states, and (ii) Search for kaonic nuclei – Kaonic Proton Matter (KPM). I conclude by reviewing briefly my own recent work, confirming Farrar’s conjecture that a deeply bound $H$ dibaryon is not ruled out by the weak-decay observation of $\mathrm{\Lambda }\mathrm{\Lambda }$ hypernuclei. However, the relatively long lifetime of such a deeply bound $H$ is much too short to qualify it for a Dark-Matter candidate.