In what is defined, in a statement published on the website of the Johannes Gutenberg University of Mainz (JGU), as a physical calculation of unprecedented precision, a team of researchers, led by Professor Hartmut Wittig, managed to calculate the radius of the proton, one of the main particles of the atom along with the neutron and electron. Despite the great advances in physics over the last few years and decades, in fact, no one had ever been able to calculate the radius of the proton with such precision. Greater uncertainty then came in 2010 when, following a special measurement of the proton radius of muon hydrogen, a significantly lower value was obtained than that found with normal hydrogen measurements.
Morainic hydrogen is a particular type of hydrogen in which the electron of the atom is replaced by the muon, its heavier «relative». Physicists, therefore, wondered if this was evidence of a «new physics» beyond the standard model or if it was just uncertainty in terms of measurements. The team of physicists of the PRISMA + Cluster of Excellence, through a particular process based on electromagnetic form factors and using the theory of lattice fields, was able to derive the radius of the proton by simulating the properties of nucleons (nucleons are the particles of the nucleus of the atom, i.e. proton or neutron) via powerful supercomputers.
The results show that the proton is most likely smaller than previously thought or calculated. However, even if defined as a calculation with unprecedented precision, the margin of error, while being very small compared to previous measurements, is still too large to completely eliminate the larger value, as Hartmut Wittig explains. one of the researchers involved in the project, who however promises to have several ideas on how to further increase the level of accuracy of these calculations.
“For the first time, we have calculated electromagnetic form factors so precisely that we are able to contribute to the proton radius debate,” explains Wittig himself.