Production of the Smallest QED Atom: True Muonium (mu^+ mu^-)

TL;DR

This paper discusses the production and potential study of true muonium, a compact pure QED system, at modern electron-positron colliders, highlighting its significance among heavy QED bound states.

Contribution

It demonstrates the feasibility of producing and studying true muonium at current colliders, a novel step in exploring heavy pure QED systems.

Findings

True muonium can be produced at modern colliders.

True tauonium is difficult to observe due to tau decay.

True muonium offers a new avenue for QED tests.

Abstract

The "true muonium" (mu^+ mu-) and "true tauonium" (tau^+ tau^-) bound states are not only the heaviest, but also the most compact pure QED systems. The rapid weak decay of the tau makes the observation of true tauonium difficult. However, as we show, the production and study of true muonium is possible at modern electron-positron colliders.