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Showing 1–3 of 3 results
Advanced filters: Author: Françoise Mulhauser Clear advanced filters

  • The 2S–2P transitions in muonic helium-4 ions are measured using laser spectroscopy and used to obtain an α-particle charge-radius value five times more precise than that from electron scattering.

    • Julian J. Krauth
    • Karsten Schuhmann
    • Franz Kottmann
    ResearchOpen Access
    Nature
    Volume: 589, P: 527-531

  • Here, a technically challenging spectroscopic experiment is described: the measurement of the muonic Lamb shift. The results lead to a new determination of the charge radius of the proton. The new value is 5.0 standard deviations smaller than the previous world average, a large discrepancy that remains unexplained. Possible implications of the new finding are that the value of the Rydberg constant will need to be revised, or that the validity of quantum electrodynamics theory is called into question.

    • Randolf Pohl
    • Aldo Antognini
    • Franz Kottmann
    Research
    Nature
    Volume: 466, P: 213-216