The Production and Discovery of True Muonium in Fixed-Target Experiments

TL;DR

This paper explores the production and decay of True Muonium in fixed-target experiments, showing that secondary mechanisms significantly increase expected yields and enhance discovery prospects.

Contribution

It provides the first detailed analysis of True Muonium production mechanisms and yield estimates relevant to upcoming fixed-target experiments.

Findings

Secondary production dominates over primary production for long-lived states.

Total yields are an order of magnitude larger than previous estimates.

Discovery prospects are very favorable.

Abstract

Upcoming fixed-target experiments designed to search for new sub-GeV forces will also have sensitivity to the never before observed True Muonium atom, a bound state of a muon and anti-muon. We describe the production and decay characteristics of True Muonium relevant to these experiments. Importantly, we find that secondary production mechanisms dominate over primary production for the long-lived 2S and 2P states, leading to total yields an order of magnitude larger than naive estimates previously suggested. We present yield estimates for True Muonium as a function of energy fraction and decay length, useful for guiding future experimental studies. Discovery and measurement prospects appear very favorable.