Controversy continues over size of subatomic particle’s radius
Institute of Nuclear Physics
Editor’s Note: After this article was published, Horbatsch and colleagues discovered an error in their analysis, which weakened the conclusions. The new calculation of the proton radius falls in between the two previous estimates, and therefore does not add much additional support for the smaller proton.
A spat over the size of the proton just got a bit more complicated.
Measurements of the proton’s radius disagree, with one group of scientists saying it’s smaller than the accepted estimate. Now, a new analysis of old data bolsters the case for a small proton. But the result may dash hopes that the discrepancy could point the way to new physics.
Scientists at York University in Toronto and the Autonomous University of Barcelona reanalyzed data from a 2010 electron scattering experiment at the Mainz Microtron in Germany, in which physicists bombarded