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 …

A laser frequency comb is a broad spectrum composed of equidistant narrow lines. Initially
invented for frequency metrology, such combs enable new approaches to spectroscopy over …

This article reviews recent developments in tests of fundamental physics using atoms and
molecules, including the subjects of parity violation, searches for permanent electric dipole …

We have performed two-photon ultraviolet direct frequency comb spectroscopy on the 1S-3S
transition in atomic hydrogen to illuminate the so-called proton radius puzzle and to …

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 …

The special least-squares adjustment of the values of the fundamental constants, carried out
by the Committee on Data for Science and Technology (CODATA) in the summer of 2017, is …

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 …

Precision measurements in Rydberg states of H with principal quantum number n in the
range between 20 and 30 are reported. In the presence of homogeneous electric fields with …

Molecular hydrogen and its isotopic and ionic species are benchmark systems for testing
quantum chemical theory. Advances in molecular energy structure calculations enable the …