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 $(\mu⁺ \mu<sup>-)$ bound state, due to the Coulomb interaction of muons from $\mu⁺ \mu<sup>-$ pairs generated in the Drell-Yan reaction of protons off nuclei of a thin foil target. The $T!M$ atoms produced in the $<sup>3S_1$ long-lived triplet state ($oT!M$) could escape from the foil to vacuum followed by their decay into $e<sup>+e<sup>-$ pairs. Observation of $e<sup>+e<sup>-$ 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.