We highlight the progress, current status, and open challenges of QCD-driven physics, in
theory and in experiment. We discuss how the strong interaction is intimately connected to a …

The extremely precise extraction of the proton radius obtained by Pohl et al. from the
measured energy difference between the 2 P and 2 S states of muonic hydrogen disagrees …

The present table contains experimental root-mean-square (rms) nuclear charge radii R
obtained by combined analysis of two types of experimental data:(i) radii changes …

1.1. Background This article reports work carried out under the auspices of the Committee
on Data for Science and Technology (CODATA) Task Group on Fundamental Constants. 1 It …

Accurate knowledge of the charge and Zemach radii of the proton is essential, not only for
understanding its structure but also as input for tests of bound-state quantum …

We review the spectrum and electromagnetic properties of baryons described as relativistic
three-quark bound states within QCD. The composite nature of baryons results in a rich …

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 …

The field of experimental positronium physics has advanced significantly in the last few
decades, with new areas of research driven by the development of techniques for trap** …

Nucleons (protons and neutrons) are the building blocks of atomic nuclei and are
responsible for more than 99% of the visible matter in the Universe. Despite decades of …

The proton charge radius has been measured since the 1950s using elastic electron–proton
scattering and ordinary hydrogen atomic spectroscopy. In 2010, a highly precise …