Precise Physics of Simple Atoms

We give a review of experimental and theoretical results on the precision study of hydrogen-like atoms with low value of the nuclear charge Z.Comment: 16 pages, invited talk at ICAP 200

Model-independent determination of the magnetic radius of the proton from spectroscopy of ordinary and muonic hydrogen

To date the magnetic radius of the proton has been determined only by means of electron-proton scattering, which is not free of controversies. Any existing atomic determinations are irrelevant because they are strongly model-dependent. We consider a so-called Zemach contribution to the hyperfine interval in ordinary and muonic hydrogen and derive a self-consistent model-independent value of the magnetic radius of the proton. More accurately, we constrain not a value of the magnetic radius by itself, but its certain combination with the electric-charge radius of the proton, namely, R_E^2+R_M^2. The result from the ordinary hydrogen is found to be R_E^2+R_M^2=1.35(12) fm^2, while the derived muonic value is 1.49(18) fm^2. That allows us to constrain the value of the magnetic radius of proton R_M=0.78(8) fm at the 10% level

Simple Atoms, Quantum Electrodynamics and Fundamental Constants

This review is devoted to precision physics of simple atoms. The atoms can essentially be described in the framework of quantum electrodynamics (QED), however, the energy levels are also affected by the effects of the strong interaction due to the nuclear structure. We pay special attention to QED tests based on studies of simple atoms and consider the influence of nuclear structure on energy levels. Each calculation requires some values of relevant fundamental constants. We discuss the accurate determination of the constants such as the Rydberg constant, the fine structure constant and masses of electron, proton and muon etc.Comment: A talk at PSAS (St. Petersburg, 2002

A self-consistent value of the electric radius of the proton from the Lamb shift in muonic hydrogen

Recently a high-precision measurement of the Lamb shift in muonic hydrogen has been performed. An accurate value of the proton charge radius can be extracted from this datum with a high accuracy. To do that a sufficient accuracy should be achieved also on the theoretical side, including an appropriate treatment of higher-order proton-structure effects. Here we consider a higher-order contribution of the finite size of the proton to the Lamb shift in muonic hydrogen. Only model-dependent results for this correction have been known up to date. Meantime, the involved models are not consistent either with the existing experimental data on the electron-proton scattering or with the value for the electric charge radius of the proton extracted from the Lamb shift in muonic hydrogen. We consider the higher-order contribution of the proton finite size in a model-independent way and eventually derive a self-consistent value of the electric radius of the proton. The re-evaluated value of the proton charge radius is found to be R_E=0.84022(56) fm

Decay of the dimuonium into a photon and a neutral pion

We compute the decay rate of dimuonium into a neutral pion and a photon. We find that approximately one in 10^5 ortho-dimuonia decays into this channel. We also determine the contribution of the virtual photon-pion loop to the hyperfine splitting in dimuonium and reproduce its leading effect in the anomalous magnetic moment of the muon.Comment: corrected and extended list of reference