The subject of this thesis is the muonic hydrogen (μ−p) Lamb shift experiment being performed at the Paul Scherrer Institute, Switzerland. Its goal is to measure the 2S − 2P energy difference in μp atoms by laser spectroscopy and to deduce the proton root–mean– square (rms) charge radius rp with 10 −3 precision, an order of magnitude better than presently known. This would make it possible to t...

Recent improvements in the determination of the running of the fine-structure constant also allow an update of the hadronic vacuum-polarization contribution to the Lamb shift. We find a shift of −3.40(7) kHz to the 1S level of hydrogen. We also comment on the contribution of this effect to the determination by elastic electron scattering of the r.m.s. radii of nuclei.

We describe a new approach to computing energy levels of a nonrelativistic bound state of two constituents with masses M and m, by a systematic expansion in powers of m/M. After discussing the method, we demonstrate its potential with an example of the radiative recoil corrections to the Lamb shift and hyperfine splitting relevant for the hydrogen, muonic hydrogen, and muonium. A discrepancy be...

The contribution of the α3 single electron-loop vacuum-polarization diagrams to the Lamb shift of the muonic hydrogen has been evaluated recently by two methods. One uses the exact parametric representation of the vacuum-polarization function while the other relies on the Padé approximation method. High numerical precision of these calculations enables us to examine the accuracy of the Monte-Ca...

Contributions to HFS and to the Lamb shift intervals of order α(Zα) induced by graphs with two radiative photons inserted in the electron line are considered. It is demonstrated that this last gauge invariant set of diagrams which are capable of producing corrections of considered order consists of nineteen topologically different diagrams. Contributions both to HFS and Lamb shift induced by gr...

Quantum theory predicts that empty space is not truly empty. Even in the absence of any particles or radiation, in pure vacuum, virtual particles are constantly created and annihilated. In an electromagnetic field, the presence of virtual photons manifests itself as a small renormalization of the energy of a quantum system, known as the Lamb shift. We present an experimental observation of the ...