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 …

Positronium (Ps) is an exotic hydrogenic atom composed of an electron bound to a positron
via the Coulomb force. Being composed of two low-mass leptons, positronium is, for all …

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 …

The proton is the primary building block of the visible Universe, but many of its properties—
such as its charge radius and its anomalous magnetic moment—are not well understood …

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 trapping …

We report on a thin-disk Yb: YAG laser made from a Q-switched oscillator and a multipass
amplifier delivering pulses of 48 mJ at 1030 nm. The peculiar requirements for this laser are …

The energy levels of hydrogen-like atomic systems are shifted slightly by the complex
structure of the nucleus, in particular by the finite size of the nucleus. These energy shifts are …

We plan to measure several 2S–2P transition frequencies in μ4He+ and μ3He+ by means of
laser spectroscopy with an accuracy of 50 ppm. This will lead to a determination of the …

Precision spectroscopy of light muonic atoms provides unique information about the atomic
and nuclear structure of these systems and thus represents a way to access fundamental …

Strong-interaction shift ε 1s and broadening Γ 1s in the pionic hydrogen atom are
determined from the energies and line widths of X-ray transitions to the 1s ground state …