2015/02/18 by Carl E. Carlson · 13 citations
Computer Science · Physics and Astronomy · #Atomic and Molecular Physics #Computational Physics and Python Applications #Neutrino Physics Research #hep-ph #physics.atom-ph
paper · pdf · doi:10.1016/j.ppnp.2015.01.002
Accepted invited review for Progress in Particle and Nuclear Physics. 28 pages, 15 figures
arxiv created 2015/02/18 · openalex publication_date 2015/02/24 · arxiv updated 2015/05/20 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
The proton size, specifically its charge radius, was thought known to about 1% accuracy. Now a new method probing the proton with muons instead of electrons finds a radius about 4% smaller, and to boot gives an uncertainty limit of about 0.1%. We review the different measurements, some of the calculations that underlie them, some of the suggestions that have been made to resolve the conflict, and give a brief overview new related experimental initiatives. At present, however, the resolution to the problem remains unknown.