True muonium

For atoms where muons have replaced one or more electrons, see muonic atom. For the onium of an electron and an antimuon, see muonium.
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A Feynman diagram showing the annihilation of an electron and a positron (antielectron), creating a photon that later decays into an new electron–positron pair.
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In particle physics, true muonium is a theoretically predicted exotic atom representing a bound state of an muon and an antimuon (μ+μ−). The existence of true muonium is well established theoretically within the Standard Model. Its properties within the Standard Model are determined by quantum electrodynamics, and may be modified by physics beyond the Standard Model.

True muonium is yet to be observed experimentally, though it may have been produced in experiments involving collisions of electron and positron beams.[1][2] The ortho-state of true muonium (i.e. the state with parallel alignment of the muon and antimuon spins) is expected to be relatively long-lived (with a lifetime of 1.8×10−12 s), and decay predominantly to an e+e− pair, which makes it possible for LHCb experiment at CERN to observe it with the dataset collected by 2025.[3]

  1. ^ Brodsky, Stanley J.; Lebed, Richard F. (2009). "Production of the smallest QED atom: True muonium (μ+μ−)". Physical Review Letters. 102 (21): 213401. arXiv:0904.2225. Bibcode:2009PhRvL.102u3401B. doi:10.1103/PhysRevLett.102.213401. PMID 19519103. S2CID 117517380.
  2. ^ Lamm, Henry; Lebed, Richard F. (2013). "True Muonium (μ+μ−) on the Light Front". Journal of Physics G: Nuclear and Particle Physics. 41 (12): 125003. arXiv:1311.3245. doi:10.1088/0954-3899/41/12/125003.
  3. ^ Vidal, Xabier Cid; Ilten, Philip; Plews, Jonathan; Shuve, Brian; Soreq, Yotam (2019). "Discovering true muonium at LHCB". Physical Review D. 100 (5): 053003. arXiv:1904.08458. Bibcode:2019PhRvD.100e3003V. doi:10.1103/PhysRevD.100.053003. S2CID 120410079.