Precise proton radius measurement confirms Standard Model with record precision
Hydrogen spectroscopy pins the proton radius at 0.84 trillionths of a millimetre and lets physicists verify quantum electrodynamics to better than a tenth of a billionth of a percent.
- The proton radius is measured at about 0.84 trillionths of a millimetre (0.84 femtometres).
- The new result rules out earlier experiments that reported a roughly 4 percent larger proton radius.
- Using this radius and muonic hydrogen data, the Standard Model prediction matched the experiment to better than a tenth of a billionth of a percent, confirming quantum electrodynamics.
- The work was led by Lothar Maisenbacher at the Max Planck Institute of Quantum Optics and published February 11 in Nature.