Towards a solution to the Proton Radius Puzzle

A model-independent analysis extracted a proton radius from scattering data that would solve the Proton Radius Puzzle

The size of the proton has become one of the most popular topics in hadronic physics in the last ten years. The possibility of measuring this quantity with extremely high precision in atomic spectroscopy made these experiments new ways of exploring the frontiers of our knowledge of the fundamental interactions. But it was after the discrepancy on the proton’s size between the extraction from electron-proton scattering experiments [0.8751(61) fm] and the spectroscopy ones [0.84087(39) fm] what really triggered the interest on the proton‘s charge radius. The observed discrepancy had a so large statistical significance that could even imply the discovery of new physics.

The observed discrepancy had a so large statistical significance that could even imply the discovery of new physics.

However, many experts in the field were very skeptical about this puzzle, claiming that the extraction of the radius in scattering experiments was not so under control as it was generally accepted by the community. In particular, these kind of extractions usually involve a model dependence that is difficult to quantify.

In our paper we were able to extract the proton radius from scattering data based on a new theoretical method that eliminates the model-dependence of the traditional analyses. What we extracted in our work was a value of 0.844(7) fm, which is in excellent agreement with the high-precision spectroscopic measurements. This result has been confirmed by the PRad Collaboration at the Jefferson Lab, according to their publication in Nature. For further details see our article here.