Speaker
Description
Exotic muonic atoms have long provided precision tests of QED and nuclear structure, yet no muonic system containing a strange quark had been explored until now. In this talk, we present a concerted theoretical and experimental investigation of muonic kaon atoms, the first muonic bound states involving strangeness. We develop a framework for $K\mu$ formation in semileptonic $D^{0}$ decays using the effective weak Hamiltonian, a helicity‑based treatment of the leptonic current, and a nonrelativistic bound‑state projection, yielding $\mathrm{BR}(D^{0}!\to(\mu K)\nu_\mu)=2.29\times10^{-10}$. In addition to weak‑decay production, we expand the treatment of QGP‑driven coalescence, in which thermal kaons and low‑momentum muons emerging from the early partonic medium recombine into bound states at late times. Because the QGP produces copious strange quarks and a significant population of soft muons, this mechanism can enhance $K\mu$ formation well beyond expectations from hadronic $D^0$ decays. Our modeling provides quantitative yield estimates and indicates that secondary‑vertex reconstruction in modern detectors is feasible. A recent measurement by the STAR Collaboration at RHIC demonstrates the formation of strange muonic atoms and their antimatter partners in Ru+Ru and Zr+Zr collisions. These results constrain the lepton source size and extract primordial low‑$p_T$ muons, showing that systematic exploration of strange‑bearing muonic atoms is now achievable.
