We report the 2018 self-consistent values of constants and conversion factors of physics and
chemistry recommended by the Committee on Data of the International Science Council …

We review experimental progress on optical atomic clocks and frequency transfer, and
consider the prospects of using these technologies for geodetic measurements. Today …

The surprising discrepancy between results from different methods for measuring the proton
charge radius is referred to as the proton radius puzzle. In particular, measurements using …

Recent mass measurements of light atomic nuclei in Penning traps have indicated possible
inconsistencies in closely related physical constants such as the proton-electron and …

At the core of the “proton radius puzzle” is a four–standard deviation discrepancy between
the proton root-mean-square charge radii (rp) determined from the regular hydrogen (H) and …

We present a new measurement of the 1 S-3 S two-photon transition frequency of hydrogen,
realized with a continuous-wave excitation laser at 205 nm on a room-temperature atomic …

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 …

This paper gives the 1998 self-consistent set of values of the basic constants and conversion
factors of physics and chemistry recommended by the Committee on Data for Science and …

Optical clocks show unprecedented accuracy, surpassing that of previously available clock
systems by more than one order of magnitude. Precise intercomparisons will enable a …

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 …