The mystery of proton size

Researchers from the universities of Coimbra and Aveiro have contributed to shedding light on the mystery of proton size in a study funded by the FCT and now published in the journal Science.

The international team calculated that the proton has a radius of 0.84087 fentometers (or 0.000 000 000 000 000 841 meters), a value that confirms measurements made in 2010 by the same researchers, but which differs from values determined by other methods. The precision now achieved is considerably greater, so the enigma of the proton's size is deepening. Once possible experimental errors have been investigated, the explanation for the discrepancies between the measurements could reveal physical phenomena in the proton not yet explained by theory, or even a new physics of the interaction between sub-atomic particles.