The mystery of proton size

Researchers from the universities of Coimbra and Aveiro have contributed to deepen the mystery of the proton size, in a study funded by FCT, now published in Science magazine.

The international team calculated that the proton has a radius of 0.84087 fentometers (or 0.000 000 000 000 000 000 841 meters), a figure that confirms measurements made in 2010 by the same researchers, but differs from values determined by other methods. The accuracy now achieved is considerably higher, so the riddle of the proton's size is now greater. After investigating possible experimental errors, the explanation of the discrepancies between the measurements may reveal physical phenomena in the proton not yet explained by theory, or even new physics of the interaction between subatomic particles.