12 research outputs found
The Lamb shift in muonic hydrogen and the proton radius
By means of pulsed laser spectroscopy applied to muonic hydrogen (ÎŒâ p) we have measured the 2S F = 1 1/2 â 2PF = 2 3/2 transition frequency to be 49881.88(76) GHz. By comparing this measurement with its theoretical prediction based on bound-state QED we have determined a proton radius value of rp = 0.84184 (67) fm. This new value is an order of magnitude preciser than previous results but disagrees by 5 standard deviations from the CODATA and the electronproton scattering values. An overview of the present effort attempting to solve the observed discrepancy is given. Using the measured isotope shift of the 1S-2S transition in regular hydrogen and deuterium also the rms charge radius of the deuteron rd = 2.12809 (31) fm has been determined. Moreover we present here the motivations for the measurements of the ÎŒ 4He + and ÎŒ 3He + 2S-2P splittings. The alpha and triton charge radii are extracted from these measurements with relative accuracies of few 10 â 4. Measurements could help to solve the observed discrepancy, lead to the best test of hydrogen-like energy levels and provide crucial tests for few-nucleon ab-initio theories and potentials
Reduction of intraspecific aggression in adult rats by neonatal treatment with a selective serotonin reuptake inhibitor
Using thermal tracers to estimate flow velocities of shallow flows: laboratory and field experiments
Liquid phase nonpoint source pollution dispersion through conveyance structures to sustainable urban drainage system within different land covers
Planar LAAPDs: temperature dependence, performance, and application in low-energy X-ray spectroscopy
The proton radius puzzle
International audienceHigh-precision measurements of the proton radius from laser spectroscopy of muonic hydrogen demonstrated up to six standard deviations smaller values than obtained from electron-proton scattering and hydrogen spectroscopy. The status of this discrepancy, which is known as the proton radius puzzle will be discussed in this paper, complemented with the new insights obtained from spectroscopy of muonic deuterium