January 19, 2025
The proton (red) has a radius of 0.84 femtometers (fm). Also shown in the figure are the three quarks that make up the proton and the gluons that hold them together. Credit: Dr. Yong-Hui Lin/University of Bonn

Protons are probably smaller than long thought

A few years ago, a novel measurement technique showed that protons are probably smaller than had been assumed since the 1990s. The discrepancy surprised the scientific community. Some researchers even believed that the Standard Model […]