Muonic bound systems, virtual particles, and proton radius

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The proton radius puzzle questions the self-consistency of theory and experiment in light muonic and electronic bound systems. Here we summarize the current status of virtual particle models as well as Lorentz-violating models that have been proposed in order to explain the discrepancy. Highly charged one-electron ions and muonic bound systems have been used as probes of the strongest electromagnetic fields achievable in the laboratory. The average electric field seen by a muon orbiting a proton is comparable to hydrogenlike uranium and, notably, larger than the electric field in the most advanced strong-laser facilities. Effective interactions due to virtual annihilation inside the proton (lepton pairs) and process-dependent corrections (nonresonant effects) are discussed as possible explanations of the proton size puzzle. The need for more experimental data on related transitions is emphasized.

Original languageEnglish
Article number012123
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number1
Publication statusPublished - Jul 27 2015

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

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