Formation of true muonium in the Drell-Yan dimuon production

Abstract

We suggest a new mechanism for the formation of true muonium ($T\!M$), the QED $(\mu^+ \mu^-)$ bound state, due to the Coulomb interaction of muons from $\mu^+ \mu^-$ pairs generated in the Drell-Yan reaction of protons off nuclei of a thin foil target. The $T\!M$ atoms produced in the $^3S_1$ long-lived triplet state ($oT\!M$) could escape from the foil to vacuum followed by their decay into $e^+e^-$ pairs. Observation of $e^+e^-$ events with a displaced vertex, and an invariant mass and decay time consistent with the mass and lifetime of the $oT\!M$ is used as a signature of the discovery of $T\!M$. We present estimates of the $T\!M$ yield and briefly discuss an experiment which could lead to such a discovery.