Submitted via IRC for Bytram
The proton might truly be smaller than was thought. Experiments on an exotic form of hydrogen first found a puzzling discrepancy with the accepted size in 2010. Now, evidence from a German and Russian team points to a smaller value for the size of the proton with ordinary hydrogen, too.
The results, which appeared on 5 October in Science, could be the first step towards resolving a puzzle that has made physicists doubt their most precise measurements, and even their most cherished theories.
[...] Pohl's team found the proton to be 4% smaller than the accepted value. Some researchers speculated that perhaps some previously unknown physics could make muons act differently than electrons. This would have required a revision of the standard model of particle physics, which predicts that muons and electrons should be identical in every way except for their masses — and might have pointed to the existence of yet-to-be-discovered elementary particles.
[...] But the German–Russian group is not quite ready to claim that the puzzle has been solved, Maisenbacher says. "We have not identified any conclusive reason why the other measurements should not be correct themselves," he says. "We would like to see more experiments from other people."
Source: Proton-size puzzle deepens
(Score: 0) by Anonymous Coward on Sunday October 08 2017, @08:51PM
Here is another one: https://www.ncbi.nlm.nih.gov/pubmed/18371493 [nih.gov]
In table 1 they show different steps are 2x and 5x faster using hydrogen, but still occurring using deuterium.