* Astronomy

True muonium, a long-theorised but never-seen atom, might be observed in future experiments, thanks to recent theoretical work by researchers at the Department of Energy's SLAC National Accelerator Laboratory and Arizona State University. True muonium was first theorised more than 50 years ago, but until now no one had uncovered an unambiguous method by which it could be created and observed.

"We don't usually work in this area, but one day we were idly talking about how experimentalists could create exotic states of matter. As our conversation progressed, we realised 'Geewe just figured out how to make true muonium'" - SLAC theorist Stanley Brodsky, who worked with Arizona State's Richard Lebed on the result.

True muonium is made of a muon and an anti-muon, and is distinguished from what's also been called "muonium" - an atom made of an electron and an anti-muon. Both muons and anti-muons are created frequently in nature when energetic particles from space strike the earth's atmosphere. Yet both have a fleeting existence, and their combination, true muonium, decays naturally into other particles in a few trillionths of a second. This makes observation of the exotic atom quite difficult.
In a paper published on Tuesday in Physical Review Letters, Brodsky and Lebed describe two methods by which electron-positron accelerators could detect the signature of true muonium's formation and decay.

Source: SLAC National Accelerator Laboratory