Muons cause confusion over proton size

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Ars Technica: Hydrogen is the simplest of atoms, formed by a single electron orbiting a single proton. Because of its simplicity, hydrogen is useful for determining many basic characteristics of particles. One such characteristic is the size of the proton, which researchers have measured to be roughly 0.88 fm. An international team of researchers has applied the same electron scattering technique normally used to measure the size of the proton to a variant of hydrogen in which the electron is replaced by a muon. The muon shares many of the same characteristics as the electron, but is 207 times heavier. Because the technique’s precision depends on mass, the muon measurements were more precise. The researchers were surprised, however, to discover that the resulting measurement of 0.84 fm was not only more precise than the value derived from electron scattering, but also smaller by more than seven standard deviations. What is causing the discrepancy is not known. But if muons interact with protons in a different way than electrons do, entirely new physics could be at work.

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  1. A new very high precision measurement of the proton radius is 5-sigma lower than QED-based expectations.

    The QED-based value is 0.877 fermi to 0.9 fermi.

    The new measurement indicates that the proton radius is 0.84 fermi.

    Decades ago Discrete Scale Relativity predicted that the proton radius
    would equal about 0.81 fermi, based on the Schwarzschild metric and
    the corrected value of G. Going to the more realistic Kerr-Newman
    metric gives a slightly higher value of 0.814 fermi.

    http://www.ejtp.com/articles/ejtpv6i22p167.pdf

    So on the proton radius test, Discrete Scale Relativity not only
    competes well with QED, it actually beats QED and gives a more
    accurate retrodiction.

    Robert L. Oldershaw
    http://www3.amherst.edu/~rloldershaw
    Discrete Scale Relativity/Fractal Cosmology

    “How can physics live up to its true greatness except by a new revolution in outlook which dwarfs all its past revolutions? And when it comes, will we not say to each other, ‘Oh, how beautiful and simple it all is! How could we ever have missed it for so long!’.”
    John Archibald Wheeler