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

TL;DR

This paper honors Toshimitsu Yamazaki's pioneering work in hadronic physics, especially in strangeness nuclear physics, highlighting discoveries of pionic-atom states and kaonic nuclei, and discusses recent work on the H dibaryon.

Contribution

It reviews Yamazaki's key contributions and presents recent findings on the H dibaryon, suggesting it is unlikely to be a dark matter candidate due to its short lifetime.

Findings

Discovery of deeply bound pionic-atom states

Search for kaonic nuclei and kaonic proton matter

Deeply bound H dibaryon unlikely as dark matter

Abstract

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 $\Lambda\Lambda$ hypernuclei. However, the relatively long lifetime of such a deeply bound $H$ is much too short to qualify it for a Dark-Matter candidate.